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1

Exciting Students About Science & Engineering ...  

E-print Network

applications include nanomachines, bioimplants, smart materials, fuel cells, genetic engineering and spaceExciting Students About Science & Engineering ... ASM MATERIALS CAMP® 2013 MATERIALS IN TODAY'S WORLD Materials science and engineering is a study of the relationship between the structure

Evans, Paul G.

2

Communicating the Excitement of Science  

ScienceCinema

In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

Michael Turner

2010-01-08

3

Exciting careers blending engineering, science, and ecology  

E-print Network

Exciting careers blending engineering, science, and ecology New Opportunities Making the world://bee.oregonstate.edu/ecoe Ecological Engineering is: · Ecosystem restoration and habitat design at multiple scales · Watershed · Phytoremediation and bioremediation · Industrial ecology · Constructed wetlands and tidal marshlands · Mitigation

Tullos, Desiree

4

RXTE observations of AGN  

NASA Technical Reports Server (NTRS)

The Rossi X-ray Timing Explorer (RXTE) observed three active galaxies during its in-orbit verification phase: NGC 4151; NGC 4945, and MCG 8-11-11. All three were detected from 2 keV to more than 100 keV by a combination of the proportional counter array (PCA) and the high energy X-ray timing experiment (HEXTE). The PCA contains five, xenon/methane, multilayer, multiwire, gas proportional counters covering the 2 to 60 keV range, while HEXTE is an array of eight NaI/CsI phoswich scintillation counters covering the 15 to 250 keV range. The three active galaxies represent the classes of Seyfert 1, Seyfert 2 and intermediate Seyfert galaxies. The results of the fitting of various models containing partial covering fractions, Compton reflection components and high energy spectral breaks are discussed.

Rothschild, R. E.; Heindl, W. A.; Blanco, P. R.; Gruber, D. E.; Marsden, D. C.; Pelling, M. R.; Jahoda, K.; Madejski, G.; Swank, J. H.; Zdziarski, A. A.; Gierlinski, M.; Hink, P. L.

1997-01-01

5

There's Nothing More Exciting than Science  

ERIC Educational Resources Information Center

The basic contention that a more imaginative, creative, and challenging approach will result in better achievement in SATs--in other words, if the children enjoy their science they will do better--was the basis of a project at Oxford Brookes University. The project was devised to encourage and enable the participating teachers to develop a

Wilson, Helen; Mant, Jenny; Coates, David

2004-01-01

6

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting  

E-print Network

Computer Science Programs Available at FAU's Treasure Coast Campus Florida Atlantic University's College of Engineering and Computer Science offers exciting degree programs in computer science.I.E.T.) and bachelor in computer science. The innovative B.I.E.T. degree program provides more hands-on, practical

Fernandez, Eduardo

7

Long Timescale Variability of AGN with RXTE  

Microsoft Academic Search

In this paper we review the very large contribution made by RXTE to our understanding of Active Galaxies (AGN). We discuss the relationship between AGN and Galactic Black Hole X-ray binary systems (GBHs) and show, by comparison of their powerspectral densities (PSDs) that some AGN are the equivalent of GBHs in their high state, rather than in their low state

I. M. McHardy; P. Uttley; R. D. Taylor; N. Seymour

2004-01-01

8

Long Timescale Variability of AGN with RXTE  

Microsoft Academic Search

In this paper we review the very large contribution made by RXTE to our understanding of Active Galaxies (AGN). We discuss the relationship between AGN and Galactic Black Hole X-ray binary systems (GBHs) and show, by comparison of their powerspectral densities (PSDs) that some AGN are the equivalent of GBHs in their `high' state, rather than in their `low' state

I. M. McHardy; P. Uttley; R. D. Taylor; N. Seymour

2004-01-01

9

More Science Activities. 20 Exciting Experiments To Do!  

ERIC Educational Resources Information Center

Science and technology affect every facet of human life. By the 21st century, society will demand that all of its citizens possess basic competencies in the fundamentals of science and the use of technology. As science increasingly becomes the dominant subject of the work place, it is important to begin developing within children an understanding

Smithsonian Institution, Washington, DC.

10

Still More Science Activities. 20 Exciting Activities To Do!  

ERIC Educational Resources Information Center

Science and technology affect every facet of human life. By the 21st century, society will demand that all of its citizens possess basic competencies in the fundamentals of science and the use of technology. As science increasingly becomes the dominant subject of the work place, it is important to begin developing within children an understanding

Smithsonian Institution, Washington, DC.

11

Using the Process and Excitement of Science and Technology to Empower Teachers and Engage their Students  

Microsoft Academic Search

Students United with NASA Becoming Enthusiastic About Math and Science (SUNBEAMS) is a Partnership between NASA Goddard Space Flight Center (GSFC) and the District of Columbia Public Schools (DCPS). It empowers teachers and inspires students with the process and excitement of science and technology. SUNBEAMS is being developed as a model urban intervention program for sixth grade teachers and their

C. J. Crannell

2002-01-01

12

Exciting youth about science and engineering : the Stirling Engine class  

E-print Network

The problem of a lack of science and engineering opportunities for youth has been identified. While other programs and attempted solutions exist, a novel approach involving creating self-contained project classes, called ...

Barragn, Patrick R

2008-01-01

13

RXTE Observations of Several Strong Flares from the TeV Blazar 1ES 1959+650  

NASA Technical Reports Server (NTRS)

Responding to the RXTE Cycle 7 NASA Research Announcement, we proposed to use the RXTE X-ray telescopes to intensively observe the TeV Gamma-ray Blazars Markarian 421, Markarian 501, 1ES 1959+650 and 1ES 1426+428, when their X-ray or TeV Gamma-ray fluxes would surpass preset trigger thresholds. In May and June, 2002, the Blazar 1ES 1959+650 (z=0.048) showed a series of spectacular X-ray and gamma-ray flares. Following the detection of a strong Gamma-ray flare on May 16 and 17 with the VERITAS 10 m Cherenkov Telescope, we invoked intensive RXTE observations, as well as complementary radio, optical and GeV/TeV Gamma-ray observations. From May 18 to August 14, more than 150 ksec RXTE observations were taken, yielding a unique data set with simultaneous RXTE and GeV/TeV Gamma-ray coverage.We used the financial support from the ADP program of NASA s Office for Space Science to perform a comprehensive analysis of the RXTE data. We studied in detail the temporal and spectral characteristics of the source. We collected multiwavelength data from a large number of collaborators, and performed a detailed cross-correlation analysis. Eventually, we interpreted the results in the framework of a Synchrotron-Self Compton model. The most important discovery of our research has been the detection of an orphan gamma-ray flare , not associated with an X-ray flare. The discovery showed conclusively that most models invoked to describe the non-thermal emission from blazars are overly simplistic.

Krawczynski, Henric

2004-01-01

14

RXTE Observations of M87: Investigating the Nonthermal Continuum  

NASA Technical Reports Server (NTRS)

This is the final report for NASA grant, awarded for the RXTE Cycle 3 Guest Observer Program, "Investigating the nonthermal continuum".It supported analysis of RXTE observations of the nearby giant elliptical galaxy M87 with the RXTE satellite. The main aim of these observations was to search for non-thermal emission from the core of M87 and the famous jet. This grant also partially funded supporting theoretical work. The observational campaign was performed in December 1997 and January 1998. The results of our detailed analysis were submitted to the Astrophysical Journal in November 1998, and accepted for publication in March 1999. The paper was published in August 1999.

Reynolds, Christopher S.

2001-01-01

15

RXTE Observations M87: Investigating the Non-Thermal Continuum  

NASA Technical Reports Server (NTRS)

This is the final report for NASA grant NAG5-7329, awarded for the RXTE Cycle 3 Guest Observer Program, "RXTE Observations of M87: Investigating the nonthermal continuum". This grant totaled $8000 and was spent over 3 years (4/1998-4/2001). It supported analysis of RXTE observations of the nearby giant elliptical galaxy M87 with the RXTE satellite. The main aim of these observations was to search for non-thermal emission from the core of M87 and the famous jet. This grant also partially funded supporting theoretical work. The observational campaign was performed in December 1997 and January 1998, and we were given the final data tape in April 1998. Sebastian Heinz (then a graduated student in our group) and I started to work on the data immediately. The results of our detailed analysis were submitted to the Astrophysical Journal in November 1998, and accepted for publication in March 1999. Tile paper was published in August, 1999. The journal reference is: A RXTE study of N187 and the core of the Virgo cluster, Reynolds C.S.,Heinx S., Fabian A.C., Begelman M.C., 1999, ApJ, 102, 1999. During this first year of the project, this grant supported Mr. Heinz's travel to the Paris Texas Symposium in December 1998, as well as providing funds for necessary maintenance of our computer system.

Reynolds, Christopher S.

2001-01-01

16

Exciting science being explored using sample environment at Spallation Neutron Source  

NASA Astrophysics Data System (ADS)

Sample environments are key to performing new and exciting science at SNS. The sample environment group takes care of everything from sample holders in furnaces to dilution refrigeration systems. Several new pieces of equipment have been added to our growing capabilities including multiple cryocoolers and cryostats along with a stand-alone cryogen free dilution refrigeration system. Our magnetic field capabilities range from 0 to 16 T on some beam lines and up to 30 T on our new pulse magnet system. With our new aerodynamic levitator system, we can reach temperatures of 2000 ^oC. Our increasing arsenal of sample environments provides avenues of new and interesting science for all users.

Debeer-Schmitt, Lisa; Mills, Rebecca; Elorfi, Saad; Christenson, John; Carmichael, Justin; Armitage, Doug; Stewart, Stephen; Rennich, Mark; Hill, Bruce; Wenzel, John; Santodonato, Louis; Plante, Brian

2012-02-01

17

RXTE Observations of MAXI J1836-194  

NASA Astrophysics Data System (ADS)

RXTE observed the recently discovered X-ray transient MAXI J1836-194 (Atel #3611, #3613, #3614) beginning at 11:08:01 (UT) on August 31, 2011, for a total of 6 ksec of good exposure over two RXTE orbits. We detect the source at a count rate of approximately 140 cts/sec (1PCU), and variability is evident with the eye. A power spectral study shows significant flat-topped, band-limited noise breaking to a power-law below 5 Hz with evidence for a weak QPO at 0.5 Hz, above the break.

Strohmayer, T. E.; Smith, E. A.

2011-08-01

18

Simultaneous Chandra and RXTE observations of the nearby bright Seyfert 2 galaxy NGC4945  

E-print Network

We analyze recent simultaneous Chandra/RXTE observations of the Seyfert 2 galaxy NGC 4945. The unprecedented spatial resolution of Chandra means we are able to separate the spectra of the nucleus, starburst and superwind regions, while the RXTE data extend the spectrum to higher energies. The extreme absorbing column of $N_H\\sim 4\\times 10^{24}$ cm$^{-2}$ means that the nucleus is only seen directly above 8--10 keV, while the lower energy spectrum from the nuclear region in Chandra is dominated by reflection. By contrast, the superwind is dominated by emission from hot plasma, but the starburst region contains both hot plasma and reflection signatures. To form a reflected spectrum requires that the starburst region contains clumps of cool, optically thick material, perhaps star forming cores, which are irradiated by 7--10 keV photons from the nucleus. Since photons of this energy are obscured along the line sight then this confirms the result of Madejski et al. (2000) that the extreme absorbtion material is disk-like rather than a torus. However, the IR/optical limits on the lack of high excitation emission lines show that by contrast the lower energy photons from the nucleus are obscured in all directions. We discuss the complex absorption structure revealed by these observations, and propose an an overall source geometry in which the nucleus is completely embedded in material with $N_H\\sim 10^{23}$ cm$^{-2}$

Chris Done; Greg M. Madejski; Piotr T. Zycki; Lincoln J. Greenhill

2003-01-20

19

Using the Process and Excitement of Science and Technology to Empower Teachers and Engage their Students  

NASA Technical Reports Server (NTRS)

Students United with NASA Becoming Enthusiastic About Math and Science (SUNBEAMS) is a Partnership between NASA Goddard Space Flight Center (GSFC) and the District of Columbia Public Schools (DCPS). It empowers teachers and inspires students with the process and excitement of science and technology. SUNBEAMS is being developed as a model urban intervention program for sixth grade teachers and their students. The teachers come to Goddard for five weeks during the summer. They partner with Goddard mentors and work much the same way that summer students do. In addition, the teachers are responsible for developing lesson plans that they pilot at their schools and post on the SUNBEAMS web site. During the school year, each teacher brings one class to Goddard for a full week of total immersion in math and science.

Crannell, Carol Jo

2002-01-01

20

Using the Process and Excitement of Science and Technology to Empower Teachers and Engage their Students  

NASA Astrophysics Data System (ADS)

Students United with NASA Becoming Enthusiastic About Math and Science (SUNBEAMS) is a Partnership between NASA Goddard Space Flight Center (GSFC) and the District of Columbia Public Schools (DCPS). It empowers teachers and inspires students with the process and excitement of science and technology. SUNBEAMS is being developed as a model urban intervention program for sixth grade teachers and their students. The teachers come to Goddard for five weeks during the summer. They partner with Goddard mentors and work much the same way that summer students do. In addition, the teachers are responsible for developing lesson plans that they pilot at their schools and post on the SUNBEAMS web site. During the school year, each teacher brings one class to Goddard for a full week of total immersion in math and science.

Crannell, C. J.

2002-06-01

21

RXTE Observation of PSR B0656+14  

E-print Network

PSR B0656+14 was observed by the {\\it Rossi X-ray Timing Explorer (RXTE)} with the proportional counter array (PCA) and the high-energy x-ray timing experiment (HEXTE) for 160 ksec during August 22 -- September 3, 1997. No pulsation was firmly found in the timing analysis, in which the contemporaneous radio ephemeris and various statistical tests were applied for searching evidence of pulsation. A marginal detection of pulsation at a confidence level of 95.5% based on the $H$-test was found with data in the whole HEXTE energy band. In the energy band of 2-10 keV the {\\it RXTE} PCA upper limits are about one order of magnitude lower than that from {\\it ASCA} GIS data. If the {\\it CGRO} EGRET detection of this pulsar is real, considering the common trait that most EGRET-detected pulsars have a cooling spectrum in hard x-ray and gamma ray energy bands, the estimated {\\it RXTE} upper limits indicate a deviation (low-energy turn-over) from a cooling spectrum starting from 20 keV or higher. It in turn suggests an outer-magnetospheric synchrotron-radiation origin for high-energy emissions from PSR B0656+14. The {\\it RXTE} PCA upper limits also suggest that a reported power-law component based on {\\it ASCA} SIS data in 1-10 keV fitted jointly with {\\it ROSAT} data, if real, should be mainly unpulsed.

Hsiang-Kuang Chang; Cheng Ho

1998-08-11

22

Gamma-ray Burst Positions from the ASM on RXTE  

E-print Network

The RXTE/ASM has detected and positioned 14 confirmed GRB bursts (at this writing, Jan. 1999) including six whose positions were comunicated to the community 2 to 32 hours after the burst. Two of these latter bursts led to measurements of optical red shifts but one, despite an easily detected x-ray afterglow, produced no detectable optical or radio afterglow.

Hale V. Bradt; Donald A. Smith

1999-05-20

23

RXTE observations of the Seyfert 2 galaxy NGC4507:  

NASA Astrophysics Data System (ADS)

Preliminary results of the RXTE observation of the Seyfert 2 Galaxy NGC4507 are presented. The observed broadband [4-100 keV] spectrum is intrinsically hard (Gamma = 1.2); an iron line is detected with a relatively high equivalent width (EW = 400 eV). The remaining calibration uncertanties are briefly discussed, as well as the scientific implications of our results.

Guainazzi, M.; Matt, G.; Piro, L.; Robba, N. R.

24

RXTE Studies of Cyclotron Lines in Accreting Pulsars  

E-print Network

RXTE Studies of Cyclotron Lines in Accreting Pulsars W.A. Heindl \\Lambda , W. Coburn \\Lambda , D, 1290 Versoix, Switzerland I INTRODUCTION Cyclotron lines in accreting X­ray pulsar spectra result from near the neutron star poles. For this reason they are known as cyclotron resonance scattering features

Barnstedt, Jürgen

25

RXTE Timing of New Energetic Pulsars for Glast (core Program)  

NASA Astrophysics Data System (ADS)

GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

26

RXTE Timing of New Energetic Pulsars for Glast  

NASA Astrophysics Data System (ADS)

GLAST is expected to detect many new gamma-ray pulsars, and hopefully solve problem of unidentified gamma-ray sources. However, detecting pulsars requires phase-coherent monitoring to provide a pulse ephemeris with which to fold the gamma-ray data. This is because of the paucity of gamma-ray photons, which demands ~year long integration times, coupled with the timing noise and glitches seen in the best GLAST targets. For radio-quiet pulsars, regular RXTE monitoring is the only practical option for coherent timing. We propose to time any radio- quiet energetic young X-ray pulsar discovered during Cycle 12 with RXTE, to provide an ephemeris for GLAST. These timing observations will be interesting for measuring braking indexes and studying glitching behavior in energetic pulsars.

Kaspi, Victoria

27

"XMM/RXTE Observations of GX 339-4"  

NASA Technical Reports Server (NTRS)

In March 2003, we performed two simultaneous XMM/RXTE observations of the black hole candidate GX 339-4. Our goal is to compare these data to our prior simultaneous RXTE/ASCA observations (Nowak, Wilms & Dove, 2002). These observations were carried out in timing mode, as opposed to burst mode, and are more complex to analyze than we expected. Specifically, the data suffered from a number of telemetry dropouts (in fact, the standard archive processing failed on these data, and more than a year passed from the time of the observations before the data was delivered to us). Furthermore, the core of the EPIC PSF suffers slightly from pileup and gain shifts. We continue to work on this data, however, and anticipate publishing it within the next academic year. Here we highlight our ongoing work and outline our plans for publication.

Nowak, M. A.; Corbel, S.; Fender, R.; Wilms, J.; Kuster, M.; Bailyn, C.; Coppi, P.

2005-01-01

28

Bat Triggered Target of Opportunity Observations with RXTE  

NASA Astrophysics Data System (ADS)

We propose to trigger RXTE PCA observations of new galactic sources discovered as part of the Hard X-ray Transient Monitor of the Burst Alert Telescope (BAT) on the Swift satellite. BAT can provide an early hard X-ray (15-50 keV) trigger on a moderately bright new source. We need the complementary high sensitivity timing data from RXTE to distinguish between various models for the origin of the new transient. By studying the temporal properties of the source in the early turn-on phase we can distinguish between the early accretion disk flow of a black hole candidate, and the periodic emission from a millisecond pulsar or longer period pulsar. This will allow us to rapidly identify the source class and to publish results from the turn-on phase of newly discovered galactic transients.

Krimm, Hans

29

RXTE Observations of LMC X-1 and LMC X-3  

NASA Technical Reports Server (NTRS)

Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3, we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

1998-01-01

30

RXTE Observations of LMC X-1 and LMC X-3  

NASA Technical Reports Server (NTRS)

Of all known persistent stellar-mass black hole candidates, only LMC X-1 and LMC X-3 consistently show spectra that are dominated by a soft, thermal component. We present results from long (170 ksec) Rossi X-ray Timing Explorer (RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra can be described by a multicolor disk blackbody plus an additional high-energy power-law. Even though the spectra are very soft (Gamma approximately 2.5), RXTE detected a significant signal from LMC X-3 up to energies of 50 keV, the hardest energy at which the object was ever detected. Focusing on LMC X-3 , we present results from the first year of an ongoing monitoring campaign with RXTE which started in 1997 January. We show that the appearance of the object changes considerably over its approximately 200 d long cycle. This variability can either be explained by periodic changes in the mass transfer rate or by a precessing accretion disk analogous to Her X-1.

Wilms, J.; Nowak, M. A.; Dove, J. B.; Pottschmidt, K.; Heindl, W. A.; Begelman, M. C.; Staubert, R.

1999-01-01

31

Echo Tomography of Hercules X-1: Mapping the Accretion Disc with RXTE and HST  

NASA Technical Reports Server (NTRS)

A paper based on the RXTE results contents the following and are ready for submission to ApJ: "Possible Detection of Companion Star Reflection from Hercules X-1 with RXTE". A paper combining July 1998 and July 1999 observations (including the RXTE results for both years) is nearly ready for submission to ApJ: The July 1998 and July 1999 Multiwavelength Campaigns on Hercules X-I/HZ Herculis. The July 1999 observations took place during an anomalous X-ray low state and the RXTE and EUVE data are consistent with X_ray reflected from the surface of the companion star.

Vrtilek, S.

2000-01-01

32

RXTE Observation of Cygnus X-1. Report 2; TIming Analysis  

NASA Technical Reports Server (NTRS)

We present timing analysis for a Rossi X-ray Timing Explorer (RXTE) observation of Cygnus X-1 in its hard/low state. This was the first RXTE observation of Cyg X-1 taken after it transited back to this state from its soft/high state. RXTE's large effective area, superior timing capabilities, and ability to obtain long, uninterrupted observations have allowed us to obtain measurements of the power spectral density (PSD), coherence function, and Fourier time lags to a decade lower in frequency and half a decade higher in frequency than typically was achieved with previous instruments. Notable aspects of our observations include a weak 0.005 Hz feature in the PSD coincident with a coherence recovery; a 'hardening' of the high-frequency PSD with increasing energy; a broad frequency range measurement of the coherence function, revealing rollovers from unity coherence at both low and high frequency; and an accurate determination of the Fourier time lags over two and a half decades in frequency. As has been noted in previous similar observations, the time delay is approximately proportional to f(exp -0.7), and at a fixed Fourier frequency the time delay of the hard X-rays compared to the softest energy channel tends to increase logarithmically with energy. Curiously, the 0.01-0.2 Hz coherence between the highest and lowest energy bands is actually slightly greater than the coherence between the second highest and lowest energy bands. We carefully describe all of the analysis techniques used in this paper, and we make comparisons of the data to general theoretical expectations. In a companion paper, we make specific comparisons to a Compton corona model that we have successfully used to describe the energy spectral data from this observation.

Nowak, Michael A.; Vaughan, Brian A.; Wilms, Joern; Dove, James B.; Begelman, Mitchell C.

1998-01-01

33

OBSERVATIONS OF SOME X-RAY TRANSIENTS WITH RXTE  

SciTech Connect

We present results of observations of several X-ray transients with RXTE in 1996-1998, namely, GRS 1739-278, XTE J1748-288, GS 1354-64, 2S1803-245 and XTE J0421+560 (CI Cam). We studied light curves and spectra of their outbursts and compared them with observations of other X-ray transients. We discuss fits of high state spectra with BMC model, and similarities and differences between black holes and neutron stars in their low state. Special attention is paid to CI Cam as possible legate for new class of X-ray transients.

K. BOROZDIN; W. PRIEDHORSKY; ET AL

1999-11-01

34

XTE Observations of Intermediate Polars: RXTE TOO Observations of Supernovae  

NASA Technical Reports Server (NTRS)

Two intermediate polar cataclysmic variables, PQ Gem and AO Psc, were observed jointly with the Rossi X-ray Timing Explorer (RXTE) and ground-based photometry. The analysis of intermediate polars (IPs) is complex because these objects exhibit light curves that behave differently as a function of energy and that behave differently when phased on the orbital or on the spin periods. The presence of two periods in one system is essentially equivalent to analyzing two different X-ray sources. A preliminary analysis of the PQ Gem data was carried out and presented at the Annapolis Workshop on Magnetic Cataclysmic Variables. The final analysis of the data were held up by problems with the background estimation. The RXTE PCA team has released a new version of the background estimator. The PQ Gem must be reanalyzed using the new background. We have also installed a spectral model that calculates the expected emission from an accretion column. That model is undergoing final testing before we apply it to the data.

Schlegel, E.; Swank, Jean (Technical Monitor)

2002-01-01

35

Analysis of RXTE data on Clusters of Galaxies  

NASA Technical Reports Server (NTRS)

This grant provided support for the reduction, analysis and interpretation of of hard X-ray (HXR, for short) observations of the cluster of galaxies RXJO658--5557 scheduled for the week of August 23, 2002 under the RXTE Cycle 7 program (PI Vahe Petrosian, Obs. ID 70165). The goal of the observation was to search for and characterize the shape of the HXR component beyond the well established thermal soft X-ray (SXR) component. Such hard components have been detected in several nearby clusters. distant cluster would provide information on the characteristics of this radiation at a different epoch in the evolution of the imiverse and shed light on its origin. We (Petrosian, 2001) have argued that thermal bremsstrahlung, as proposed earlier, cannot be the mechanism for the production of the HXRs and that the most likely mechanism is Compton upscattering of the cosmic microwave radiation by relativistic electrons which are known to be present in the clusters and be responsible for the observed radio emission. Based on this picture we estimated that this cluster, in spite of its relatively large distance, will have HXR signal comparable to the other nearby ones. The planned observation of a relatively The proposed RXTE observations were carried out and the data have been analyzed. We detect a hard X-ray tail in the spectrum of this cluster with a flux very nearly equal to our predicted value. This has strengthen the case for the Compton scattering model. We intend the data obtained via this observation to be a part of a larger data set. We have identified other clusters of galaxies (in archival RXTE and other instrument data sets) with sufficiently high quality data where we can search for and measure (or at least put meaningful limits) on the strength of the hard component. With these studies we expect to clarify the mechanism for acceleration of particles in the intercluster medium and provide guidance for future observations of this intriguing phenomenon by instrument on GLAST. The details of the nonthermal particle population has important implications for the theories of cluster formation, mergers and evolution. The results of this work were first presented at the High Energy Division meeting of the American astronomical Society at Mt. Tremblene, Canada (Petrosian et al. 2003). and in an invited review talk at the General Assembly of the International Astronomical Union at Sydney, Australia (Petrosian, 2003). A paper describe the observations, the data analysis and its implication is being prepared for publication in the Astrophysical Journal.

Petrosian, Vahe

2004-01-01

36

A bright thermonuclear X-ray burst simultaneously observed with Chandra and RXTE  

E-print Network

The prototypical accretion-powered millisecond pulsar SAX J1808.4?3658 was observed simultaneously with Chandra-LETGS and RXTE-PCA near the peak of a transient outburst in November 2011. A single thermonuclear (type-I) ...

in t Zand, J. J. M.

37

Science Fair Competition Generates Excitement and Promotes Creative Thinking in Japan  

ERIC Educational Resources Information Center

Educators in the U.S. and Japan have developed an international program to promote creative thinking in science. Their program includes a science fair component. This paper (which has been presented in both the U.S. and Japan) discusses creativity and describes a science fair activity, that the authors recently carried out in Japan. The special

Barry, Dana M.; Kanematsu, Hideyuki

2006-01-01

38

The Excitement and Wonder of Teaching Science: What Pre-Service Teachers Learn from Facilitating Family Science Night Centers  

ERIC Educational Resources Information Center

In this study, pre-service teachers facilitated stations at a family science night as a context to learn to identify, assess, and use children's science ideas. Assessment is already difficult in K-12 classrooms. Assessing learning in informal learning environments adds the complication that participation is largely voluntary. As such, controlling

Harlow, Danielle B.

2012-01-01

39

ADVANCES IN THE RXTE PROPORTIONAL COUNTER ARRAY CALIBRATION: NEARING THE STATISTICAL LIMIT  

SciTech Connect

During its 16 years of service, the Rossi X-Ray Timing Explorer (RXTE) mission has provided an extensive archive of data, which will serve as a primary source of high cadence observations of variable X-ray sources for fast timing studies. It is, therefore, very important to have the most reliable calibration of RXTE instruments. The Proportional Counter Array (PCA) is the primary instrument on board RXTE which provides data in 3-50 keV energy range with submillisecond time resolution in up to 256 energy channels. In 2009, the RXTE team revised the response residual minimization method used to derive the parameters of the PCA physical model. The procedure is based on the residual minimization between the model spectrum for Crab Nebula emission and a calibration data set consisting of a number of spectra from the Crab and the on-board Am{sub 241} calibration source, uniformly covering the whole RXTE mission operation period. The new method led to a much more effective model convergence and allowed for better understanding of the PCA energy-to-channel relationship. It greatly improved the response matrix performance. We describe the new version of the RXTE/PCA response generator PCARMF v11.7 (HEASOFT Release 6.7) along with the corresponding energy-to-channel conversion table (version e05v04) and their difference from the previous releases of PCA calibration. The new PCA response adequately represents the spectrum of the calibration sources and successfully predicts the energy of the narrow iron emission line in Cas-A throughout the RXTE mission.

Shaposhnikov, Nikolai [CRESST and Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Jahoda, Keith; Markwardt, Craig; Swank, Jean; Strohmayer, Tod, E-mail: nikolai.v.shaposhnikov@nasa.gov [Astrophysics Science Division, Goddard Space Flight Center, NASA, Greenbelt, MD 20771 (United States)

2012-10-01

40

Life in the Universe: Foundation for exciting multidisciplinary science activities for middle and elementary school classes  

NASA Technical Reports Server (NTRS)

Young students find extra-terrestrial life one of the most intriguing of all topics. A project funded by the National Science Foundation and NASA, and administered by the SETI Institute, is underway to devise science lessons for grades 3-9 that draw upon this fascination. The lessons are designed by teachers and persons with long experience at curriculum design, tested in classrooms, revised and retested. Six guides, each containing some 6-10 science lessons, will be finished by summer, 1994.The theme Life in the Universe lends itself naturally to integrated treatment of facts and concepts from many scientific disciplines. The lessons for two completed guides span the origin of planet systems, evolution of complex life, chemical makeup of life, astronomy, spectroscopy, continental drift, mathematics and SETI (Search for Extra-Terrestrial Intelligence). All lessons are hands-on, interesting, and successful.

Milne, D.; O'Sullivan, K.

1994-01-01

41

RXTE dips yield better orbital period determination for MAXI J1659-152  

NASA Astrophysics Data System (ADS)

We analyzed 32 RXTE/PCA observations of MAXI J1659-152 (Negoro et al. 2010, ATel #2873; Mangano et al. 2010, GCN #11296) from UT 2010 Sep 28 through to 2010 Oct 11. The total exposure is 72.5 ks. We produced light curves from PCU2 with 16-s bins over the full PCA range and over the 2-4.5 keV range. Since the average count rate of the source increases secularly because of the ongoing outburst, for each observation interval (corresponding to an RXTE orbit) we subtracted the mean count rate.

Belloni, T. M.; Muoz-Darias, T.; Kuulkers, E.

2010-10-01

42

X-ray periodicities in sources observed by the RXTE ASM  

E-print Network

The X-ray intensities measured from 230 X-ray sources observed by the RXTE All-Sky Monitor (ASM) were analyzed for periodic behavior. The ASM has been observing sources for nine years in the 1.5-12 keV energy range. In ...

Shivamoggi, Vasudha B

2005-01-01

43

News Conference: Brecon hosts 10th teacher's conference Summer school: Science summer school heads to Crete Award: The Corti Science Prize Radioactivity: Scottish beach is no beta off Workshop: Heureka project promotes teaching Experiments: Spanish project proves that learning science can be exciting Lecture: IOP schools lecture journeys from x-rays to antimatter Correction to the news item 'Delegates experience universality' Forthcoming events  

NASA Astrophysics Data System (ADS)

Conference: Brecon hosts 10th teacher's conference Summer school: Science summer school heads to Crete Award: The Corti Science Prize Radioactivity: Scottish beach is no beta off Workshop: Heureka project promotes teaching Experiments: Spanish project proves that learning science can be exciting Lecture: IOP schools lecture journeys from x-rays to antimatter Correction to the news item 'Delegates experience universality' Forthcoming events

2012-01-01

44

Combined long and short timescale X-ray variability of NGC4051 with RXTE and XMM-Newton  

Microsoft Academic Search

We present a comprehensive examination of the X-ray variability of the narrow line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent monitoring observations by RXTE with a >100ks continuous observation by XMM-Newton and so present a powerspectral density (PSD) covering an unprecedent frequency range of over 6.5 decades from <10?8 to >10?2 Hz. The combined RXTE

I. M. McHardy; I. E. Papadakis; P. Uttley; K. O. Mason; M. J. Page

2004-01-01

45

RXTE shows a transition to the high-soft state in MAXI J1659-152  

NASA Astrophysics Data System (ADS)

The last two RXTE observations of the new galactic black hole candidate MAXI J1659-152 (Atels #2873,#2877,#2881) performed on October 17, 2010, 04:16 UT and 18:52 UT have clearly shown changes in the source spectral and variability properties consistent with a transition to the high soft state. Specifically, the power density spectrum have shown the rms variability level of about 5% presented by the low frequency red noise only.

Shaposhnikov, Nikolai; Yamaoka, Kazutaka

2010-10-01

46

RXTE Observation of PSR B1706-44 and Implications for Theoretical Models of Pulsar Emission  

E-print Network

We report on results of an observation with the Rossi X-Ray Timing Explorer (RXTE) of PSR B1706-44 with a live time of 132 ks, to search for pulsed X-ray emission. PSR B1706-44 is a radio and high-energy gamma-ray pulsar (detected by EGRET), but no pulsed emission has been detected in the X-ray band. Since most of the other known gamma-ray pulsars emit pulsed X-rays, it is expected that PSR B1706-44 would also be an X-ray pulsar. However, while the ROSAT PSPC detected a source at the pulsar position, it did not detect pulsations, giving a pulsed fraction upper limit of 18%. The RXTE observations to search for modulation at the pulsar period were carried out in November 1996 and May 1997, during the low states of the nearby X-ray binary 4U1705-44. No significant modulation was detected at the pulsar period, giving an upper limit of 10^{-6} photons cm^{-2} s^{-1} keV^{-1} in the interval 9 keV < E < 18.5keV. The implications of this upper limit of the pulsed flux from the RXTE observation, taken together with multiband observations of this pulsar are examined in the context of theoretical models of pulsar particle acceleration zones.

A. Ray; A. K. Harding; M. S. Strickman

1998-06-15

47

Millisecond dips in the RXTE/PCA light curve of Sco X-1 and TNO occultation  

E-print Network

Millisecond dips in the RXTE/PCA light curve of Sco X-1 were reported recently (Chang et al. 2006), which were interpreted as the occultation of X-rays from Sco X-1 caused by Trans-Neptunian Objects (TNO) of hundred-meter size. Inconclusive signatures of possible instrumental effects in many of these dip events related to high-energy cosmic rays were later found (Jones et al. 2006) and the TNO interpretation became shaky. Here we report more detailed analysis aiming at distinguishing true occultation events from those related to cosmic rays. Based on some indicative criteria derived from housekeeping data and two-channel spectral information, we suggest that about 10% of the dips are probable events of occultation. The total number of TNOs of size from 60 m to 100 m is estiamted to be about 10^{15} accordingly. Limited by the coarser time resolution of standard data modes of RXTE/PCA, however, definite results cannot be obtained. Adequately configured observations with RXTE or other new instruments in the future are very much desired.

Hsiang-Kuang Chang; Jau-Shian Liang; Chih-Yuan Liu; Sun-Kun King

2007-01-30

48

A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL  

E-print Network

In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type I) outburst with an average flux F(5-100keV)~400mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. The pulse period P is measured to be 103.39315(5)s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at E_1~45keV and E_2~100keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be B~4x10^12G.

I. Caballero; P. Kretschmar; A. Santangelo; R. Staubert; D. Klochkov; A. Camero; C. Ferrigno; M. H. Finger; I. Kreykenbohm; V. A. McBride; K. Pottschmidt; R. E. Rothschild; G. Schoenherr; A. Segreto; S. Suchy; J . Wilms; C. A. Wilson

2007-02-20

49

1018 BioScience December 2001 / Vol. 51 No. 12 The 21st century is an exciting time for biological  

E-print Network

the National Science Foundation. Because biocomplexity has so rapidly devel- oped,it seems appropriate of biocomplexity, the term has most frequently been associated with the recent National Science Foundation program with the Biocomplexity com- petition. Thomas J. Baerwald is senior science advisor and program director at the National

50

A Global Look at Reflection in Black-Hole X-ray Binaries Using RXTE  

NASA Astrophysics Data System (ADS)

Spectral reflection is ubiquitous in black-hole X-ray binaries, and is produced by the coronal hard X-ray emission illuminating the cooler accretion disk. The observed interplay between coronal and reflection spectral components provides insight into the geometry of the corona - an attribute which is presently only weakly constrained We present first results from a new campaign analyzing all RXTE PCU-2 spectra of accreting stellar-mass black holes. A simple but self-consistent treatment of disk, coronal, and reflection emission highlights changes evident in the coronal geometry between soft and hard spectral states.

Steiner, James F.; Garcia, Javier; Reis, Ruben C.; McClintock, Jeffrey E.

2014-08-01

51

Cryogenic exciter  

DOEpatents

The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

2012-03-13

52

Surface Science Letters Nature of the excited states of the rutile TiO2(110) surface  

E-print Network

phenomena (work function, surface potential, surface states, etc.); Titanium oxide; Water 1. Introduction The nature of the electronically excited states on titanium dioxide surface is important for under- standing solution and decom- posing water molecules into hydrogen and oxygen [1]. This property was attributed

Truong, Thanh N.

53

Some Early Results from the Rossi X-ray Timing Explorer (RXTE)  

E-print Network

The Rossi X-ray Timing Explorer (RXTE) was successfully launched on 1995 December 30 and has been operational since that time. Its three instruments are probing regions close to compact objects, degenerate dwarfs, neutron stars, stellar black holes and the central engines of AGN. Temporal studies with the ASM and PCA have already yielded rich results which pertain to the environs, evolution, and nature of the compact objects in galactic systems. Here I review some selected results from these instruments, as obtained by various RXTE observers. The ASM is providing detailed light curves of about 60 detected sources and has uncovered new temporal/spectral states of galactic binary systems. The bizarre behavior of the possibly very young binary system, Cir X-1, is being revealed in detail by both the ASM and the PCA. A rare high/soft state of the black-hole candidate, Cyg X-1 provides new insight into the nature of the low/high transitions in black-hole binaries. The PCA has made possible the discovery of oscillations near 1 kHz in ten low-mass X-ray binary systems. These are most probably direct indicators of the neutron-star spin in some cases and probably indirect indicators in others. Studies of microquasars have unveiled a host of new temporal phenomena which may provide links between accretion processes and the radio jets in these systems.

Hale Bradt

1997-03-26

54

Observing the Granularity in the X-ray Background with RXTE  

NASA Astrophysics Data System (ADS)

The X-ray diffuse background (XRB) is widely held to originate largely from distant active galaxies. Counts of sources in survey missions and from fluctuation studies have given support to this view, but no deep studies have been performed in the 10-60 keV band where most of the emission occurs. During normal observations, the HEXTE instrument on RXTE makes nearly simultaneous observations of two pairs of background fields separated by 3.0 degrees. Differences in fluxes from these pairs of background fields can be used to detect a source population much deeper, a distance of z=0.3, than can be studied from individual detections. Using the ensemble of all long RXTE pointings, a measurement of the fluctuations in the XRB in wide energy bands above 15 keV can be made. Tails of the distribution of differences between pairs of fields are dominated by sources that occur at a spatial density of one source per field of view. For the HEXTE instrument this is one per square degree. A number density and spectrum inferred from these data will constrain virtually all the current models of the origin of the X-ray background, provided that the limit of counting errors can be approached. We present here the result of a number of tests for systematics which have been performed on the 2-4 million seconds of data so far obtained, which is 10-20 percent of the expected total.

MacDonald, D. R.; Zych, A. D.; Gruber, D. E.; Blanco, P. R.; Heindl, W. A.; Marsden, D.; Rothschild, R. E.; Boldt, E.; Mushotzky, R. F.; Fabian, A. C.; Antunes, A.; Smith, E.

1996-12-01

55

MULTIWAVELENGTH OBSERVATIONS OF LS I +61{sup 0} 303 WITH VERITAS, SWIFT, AND RXTE  

SciTech Connect

We present results from a long-term monitoring campaign on the TeV binary LSI +61{sup 0} 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between 2006 September and 2008 February. The binary was observed by VERITAS to be variable, with all integrated observations resulting in a detection at the 8.8{sigma} (2006/2007) and 7.3{sigma} (2007/2008) significance level for emission above 500 GeV. The source was detected during active periods with flux values ranging from 5% to 20% of the Crab Nebula, varying over the course of a single orbital cycle. Additionally, the observations conducted in the 2007-2008 observing season show marginal evidence (at the 3.6{sigma} significance level) for TeV emission outside the apastron passage of the compact object around the Be star. Contemporaneous hard X-ray observations with RXTE and Swift show large variability with flux values typically varying between 0.5 and 3.0 x10{sup -11} erg cm{sup -2} s{sup -1} over a single orbital cycle. The contemporaneous X-ray and TeV data are examined and it is shown that the TeV sampling is not dense enough to detect a correlation between the two bands.

Acciari, V. A. [Department of Life and Physical Sciences, Galway-Mayo Institute of Technology, Dublin Road, Galway (Ireland); Aliu, E. [Department of Physics and Astronomy and the Bartol Research Institute, University of Delaware, Newark, DE 19716 (United States); Arlen, T.; Chow, Y. C. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Bautista, M.; Cogan, P. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Beilicke, M.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Benbow, W. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Boettcher, M. [Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Bradbury, S. M.; Daniel, M. [School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT (United Kingdom); Butt, Y.; Butt, Y. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cannon, A. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Cesarini, A. [School of Physics, National University of Ireland, Galway (Ireland); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Colin, P. [Physics Department, University of Utah, Salt Lake City, UT 84112 (United States); Cui, W. [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)], E-mail: awsmith@hep.anl.gov (and others)

2009-08-01

56

RXTE-based 35 Day Cycle Turn-on Times for Hercules X-1  

NASA Astrophysics Data System (ADS)

The 35 day X-ray cycle of Hercules X-1 (Her X-1) has been the subject of intense study since its discovery over 30 years ago. This work summarizes the results of determination of 35 day cycle turn-on (TO) times based on Rossi X-Ray Timing Explorer (RXTE)/All-Sky Monitor (ASM) observations of Her X-1. We apply a cross-correlation method to the entire (RXTE/ASM) Her X-1 database acquired between 1996 February 20 and 2009 December 18. We obtain new TO times for 147 cycles, 94 of which have well-determined times. The results reveal a uniform distribution of TO times with orbital phase. This does not support previous results that suggest TO times cluster around a specific orbital phase, such as 0.2 or 0.7. We also find 35 day cycle lengths ranging from 33.2 days to 36.7 days, and an average cycle length of 34.7 days.

Leahy, Denis A.; Igna, Ciprian D.

2010-04-01

57

Using Remote Sensing Technology, Web Casts, and Participation in a Valuable Research Project to Jazz Teachers and Excite Students About Science  

NASA Astrophysics Data System (ADS)

Scientific education of primary and secondary school children has become a topic of concern in Ohio and throughout the United States. So with that in mind, how do you get students excited about learning science? One route is to inform and jazz teachers about current technology! The University of Toledo has hosted three one-week, NASA and OhioView sponsored professional development institutes entitled, Observing Earth from Space, for teachers from grades K-12 during July 2000, 2001, and 2002. Sixty-seven teachers from the Upper Midwest and Kansas with Earth Science, Social Studies, and Physics backgrounds attended. Each participant acquired new ideas, plenty of educational materials, and posters of satellite imagery. The teachers received basic training in remote sensing, global positioning systems, digital elevation models, and weather observing techniques and learned about useful remote sensing applications. This instruction was conducted through: 1) presentations given by research scientists, 2) integration of the learned content into authentic, hands-on lesson plans, and 3) participation in a learning adventure, where their students collected real-time earth science data at their respective schools while university research scientists gathered corresponding satellite imagery. The students observations were submitted via a simple Web interface: www.remotesensing.utoledo.edu. One of the very exciting platforms used to communicate with the teachers and students throughout the school year were live Web Casts sponsored by NASA Glenn Research Center. The students data have successfully assisted in the validation of cloud/snow remote sensing algorithms, and next year the students observations will include various surface temperature readings. The participation in a cutting-edge technology workshop and in an important global climate change research project, applicable in the classroom, has added another worthwhile dimension to the learning process and career awareness for both the teachers and their students.

Benko, T. M.; Czajkowski, K. P.; Struble, J.; Zhao, L.

2002-12-01

58

Map, Excite, Jump, and Measure: An Outreach Activity That Utilizes Seismology to Engage Students in Technology, Science, Engineering, and Mathematics  

NASA Astrophysics Data System (ADS)

We designed and will present a lesson plan to teach students STEM concepts through seismology. The plan addresses new generation science standards in the Framework for K-12 Science Education as well AAAS Benchmarks for Science Literacy. The plan can be executed at a facility with a seismometer in a research facility or university, on a field trip, but it can also be used in a school setting with a school seismometer. Within the lesson plan, the students first use technology to obtain earthquake location data and map them. Next, the students learn about the science of earthquakes, which is followed by an engineering activity in which the students design a hypothetical seismometer and interact with the actual seismometer and live data display. Lastly the students use mathematics to locate an earthquake through trilateration. The lesson plan has been fine-tuned through implementation with over 150 students from grades 3-12 from the Chicago area.

van der Lee, S.; Tekverk, K.; Rooney, K.; Boxerman, J.

2013-12-01

59

A Year of Hands-on Science: Exciting Theme Units with More Than 100 Activities, Projects, and Experiments To Make Science Come Alive.  

ERIC Educational Resources Information Center

This book contains 18 themed teaching units with 2 themes per chapter, organized seasonally around the traditional school year. Each theme includes natural connections and hands-on science activities that correspond to what children are already observing in their world. Each chapter begins with highlights of the month and a reproducible "Science

Kepler, Lynne; Novelli, Joan, Ed.

60

Peculiar Outburst of A 0535+26 Observed with INTEGRAL, RXTE and Suzaku  

NASA Technical Reports Server (NTRS)

A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occurred around the periastron passage of the source. but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from M.ID 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab. and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL. RXTE and Suzaku. First results of these observations are presented. with special emphasis on the cyclotron lines present in the X-ray spectrum of the source. as well as in the pulse period and energy dependent pulse profiles of the source

Caballero, I.; Pottschmidt, K.; Barragan, L.; Ferrigno, C.; Kretschmar, P.; Suchy, S.; Wilms, J.; Santangelo, A.; Kreykenbohm, I.; Rothschild, R.; Klochkov, D.; Staubert, R.; Finger, M. H.; Camero-Arranz, A.; Makishima, K.; Enoto, T.

2009-01-01

61

Observations of the blazar 1ES 2344+514 with RXTE, Swift, and VERITAS  

NASA Astrophysics Data System (ADS)

We present multiwavelength observations of the high-frequency peaked blazar 1ES 2344+514 from October 2007 to January 2008. Very high energy (VHE) ?-ray observations with VERITAS resulted in strong detections on several nights, showing nightly variability in the integral flux above 300 GeV Near simultaneous X-ray observations with RXTE PCA and Swift XRT revealed moderately correlated flux variability between the X-ray and VHE ?-ray bands. Swift UVOT and XRT observations showed a significant shift to higher synchrotron peak energies at increased peak fluxes. Results are discussed from Synchrotron Self-Compton modeling of the near-simultaneous UV to TeV ?-ray spectral energy distributions.

Grube, J.

2008-12-01

62

A DOUBLE-PEAKED OUTBURST OF A 0535+26 OBSERVED WITH INTEGRAL, RXTE, AND SUZAKU  

SciTech Connect

The Be/X-ray binary A 0535+26 showed a normal (type I) outburst in 2009 August. It is the fourth in a series of normal outbursts associated with the periastron, but is unusual because it presented a double-peaked light curve. The two peaks reached a flux of {approx}450 mCrab in the 15-50 keV range. We present results of the timing and spectral analysis of INTEGRAL, RXTE, and Suzaku observations of the outburst. The energy-dependent pulse profiles and their evolution during the outburst are studied. No significant differences with respect to other normal outbursts are observed. The centroid energy of the fundamental cyclotron line shows no significant variation during the outburst. A spectral hardening with increasing luminosity is observed. We conclude that the source is accreting in the sub-critical regime. We discuss possible explanations for the double-peaked outburst.

Caballero, I. [Laboratoire AIM, CEA/IRFU, CNRS/INSU, Universite Paris Diderot, CEA DSM/IRFU/SAp, F-91191 Gif-sur-Yvette (France); Pottschmidt, K.; Marcu, D. M. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Barragan, L.; Wilms, J.; Kreykenbohm, I. [Dr. Karl Remeis-Sternwarte and ECAP, FAU Erlangen-Nuremberg, Sternwartstr. 7, D-96049 Bamberg (Germany); Ferrigno, C. [ISDC Data Centre for Astrophysics, University of Geneva, Chemin d'Ecogia 16, CH-1290 Versoix (Switzerland); Klochkov, D.; Suchy, S.; Santangelo, A.; Staubert, R. [Institut fuer Astronomie und Astrophysik, Sand 1, D-72076 Tuebingen (Germany); Zurita Heras, J. A. [Francois Arago Centre, APC (UMR 7164 Universite Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris), 13 rue Watt, F-75205 Paris Cedex 13 (France); Kretschmar, P. [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada, E-28080 Madrid (Spain); Fuerst, F. [Space Radiation Lab, California Institute of Technology, MC 290-17 Cahill, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Rothschild, R. [Center for Astrophysics and Space Science, UCSD, La Jolla, CA 92093 (United States); Finger, M. H. [National Space Science and Technology Center, 320 Sparkman Drive NW, Huntsville, AL 35805 (United States); Camero-Arranz, A. [Institut de Ciencies de l'Espai (IEEC-CSIC), Campus UAB, Fac. de Ciencies, Torre C5, parell, 2a planta, E-08193 Barcelona (Spain); Makishima, K. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Enoto, T. [Cosmic Radiation Laboratory, RIKEN, 2-1, Hirosawa, Wako City, Saitama 351-0198 (Japan); Iwakiri, W., E-mail: isabel.caballero@cea.fr [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); and others

2013-02-20

63

Neutron Stars and Black Holes Seen with the Rossi X-Ray Timing Explorer (RXTE)  

NASA Technical Reports Server (NTRS)

Astrophysical X-rays bring information about location, energy, time, and polarization. X-rays from compact objects were seen in the first explorations to vary in time. Eclipses and pulsations have simple explanations that identified the importance of X-ray binaries and magnetic neutron stars in the first decade of X-ray astronomy. The dynamics of accretion onto stellar and supermassive black holes and onto neutron stars with relatively low magnetic fields shows up as more complex variations, quasi-periodic oscillations, noise with characteristic frequency spectra, broad-band changes in the energy spectra. To study these variations, RXTE instruments needed to have large area and operational flexibility to find transient activity and observe when it was present. Proportional counters and Phoswich scintillators provided it in a modest mission that has made textbook level contributions to understanding of compact objects. The first seen, and the brightest known, X-ray binary, Sco X-1 is one of a class of neutron stars with low mass companions. Before RXTE, none of these had been seen to show pulsations, though they were hypothesized to be the precursors of radio pulsars with millisecond periods and low magnetic fields. RXTE's large area led to identifying coherent millisecond pulsars in a subset which are relatively faint transients. It also led to identifying short episodes of pulsation during thermonuclear bursts, in sources where a steady signal is not seen. The X-ray stage verifies the evolution that produces millisecond radio pulsars.Masses and radii of neutron stars are being determined by various techniques, constraining the equation of state of matter at nuclear densities. Accretion should lead to a range of neutron star masses. An early stage of superstrong magnetic field neutron stars is now known to produce X-ray and gamma-ray bursts in crust quakes and magnetic field reconnection releases of energy. Soft Gamma Repeaters, Anomolous X-ray Pulsars, and high magnetic field rotation-powered pulsars are all now called magnetars, because they have pulse periods indicating they are slowing down as they would with magnetic dipole radiation for a surface field above 5x1013 gauss. The accretion disk has been connected to the launching of radio jets from black holes, and even from neutron stars. Estimates of the angular momenta of black holes are being made from different approaches, modelling a high frequency oscillation that may be related to how close the inner part of the accretion disk is to the black hole, modelling the continua spectra of the X-ray emission, and modeling the emission of red-shifted iron that may be emitted from the accretion disk. These investigations require early discovery of the black hole transient with the All Sky Monitor on RXTE or other monitoring information, frequent extended observations, and coordinated observations with missions that give higher energy resolution, or radio and infrared information.

Swank, Jean

2008-01-01

64

A study of RXTE and BeppoSAX observations of Cyg X-3  

E-print Network

We present an analysis of Cyg X-3 data from RXTE/PCA,HEXTE and ASM, supplemented by a selected spectrum from BeppoSAX. We fit the PCA/HEXTE spectra from 1996-2000 by a model including hybrid Comptonization, reflection and absorption, and classify them into hard, intermediate and soft states. Apart from the very strong absorption in Cyg X-3, the spectra resemble those of GRS 1915+105. The soft and intermediate state spectra require the presence of nonthermal Comptonizing electrons. We then study the radiative processes at soft X-rays with a hard-state spectrum from BeppoSAX modeled including emission from a photoionized plasma.

A. Szostek; A. A. Zdziarski

2004-01-14

65

A Simple Method to Improve the Quality of RXTE PCA Spectra  

NASA Astrophysics Data System (ADS)

We fitted at once all of the several hundred RXTE PCA spectra of the Crab to a simple power-law model; the total number of counts in the composite spectrum is >10^9. We then used the spectrum of fit residuals (data/model) to correct large samples of spectra of G 339-4, H1743-322, and XTE J1550-564. The correction improved the quality of all the fits, and the improvement was dramatic for spectra with >10^7 counts. The Crab residual spectrum is somewhat different for each of the five PCA detectors, but it was relatively stable during the course of the 16-year mission. We provide public software that automates the process of applying the correction to PCA data and recommend that the correction be applied to all spectra with >10^6 counts.

Garcia, Javier; McClintock, Jeffrey E.; Steiner, James F.; Remillard, Ronald A.; Grinberg, Victoria

2014-06-01

66

How to Use a Bed of Nails to Facilitate Excitement during a Science Road Show Presentation at Local Schools  

NASA Astrophysics Data System (ADS)

The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.

Pena, Fabian; Kridler, Shawn; Berger, Pete

2008-03-01

67

P cell excitability AP excitability  

E-print Network

AP (mV) P (mV) DP(15) (ipsi) DP(15) (contra) ba d P cell excitability Vm I (nA) AP excitability Vm) Measurement of input resistance of P and cell 212 and the amplitude of the P-to-cell 212 synaptic potential. We hyperpolarized cell 212 to prevent it from generating action potentials during P cell stimulations

Gaudry, Quentin

68

The Crab Pulsar Observed by RXTE: Monitoring the X-Ray to Radio Delay for 16 Years  

NASA Technical Reports Server (NTRS)

In 2004 we published the results of monitoring the Crab Pulsar by RXTE. At that time we determined that the primary pulse of the pulsar at X-ray energies precedes its radio counterpart by about 0.01 period in phase or approximately 330 micro seconds. However, we could not establish unambiguously whether the delay is in phase or due to a difference in pathlength. At this time we have twice the time baseline we had in 2004 and we present the same analysis, but now over a period of 16 years, which will represent almost the full mission and the best that will be available from RXTE. The full dataset shows that the phase delay has been decreasing faster than the pulse frequency over the 16 year baseline and that there are variations in the delay on a variety of timescales.

Rots, Arnold; Jahoda, Keith

2012-01-01

69

Highlights from RXTE after 2.5 Years: Neutron-star Spins at KiloHertz Frequencies, Microquasars and More  

E-print Network

The Rossi X-ray Timing Explorer (RXTE) satellite was launched on 30 December 1995. It has made substantial contributions pertaining to compact objects and their environs. Broad-band spectral and short-time-scale temporal studies are exploring the effects of General Relativity in the regime of strong gravity. We present a brief outline of the principal contributions and then give a general overview of two new areas of x-ray astronomy that have proven by RXTE to be very fruitful: accreting neutron stars with millisecond spin periods and microquasars. The former pertains to the spin evolution of low-mass x-ray binaries and the equations of state of neutron stars while the latter is lends insight to disk-jet interactions in galactic black-hole binary systems.

Hale V. Bradt

1999-01-13

70

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

71

A Simultaneous XMM/RXTE Observation of the BLRG 3C 111  

NASA Astrophysics Data System (ADS)

We present the results of a simultaneous XMM-Newton and RXTE observation of the Broad-Line Radio Galaxy 3C 111. We find that the Compton reflection bump is extremely weak, however broad residuals are clearly present in the spectrum near the Fe K ? line. When fit with a Gaussian emission line, the feature has an equivalent width of 6020 eV and FWHM of 40,00020,000 km/s. The width of the line suggests an origin in the inner accretion disk, which is, however, inconsistent with the lack of Compton reflection. An alternative possibility, which is more appealing because it is self-consistent, is that the broad residuals are an artifact of partial covering of the primary X-ray source. The data are well fitted by a model that includes an absorber with a column density of 1023 cm-2 covering 20% of the source. A weak, unresolved Fe K ? line remains which is consistent with being formed by transmission through the partial covering absorber or reflection from a distant, Compton-thin molecular torus. This research was funded by XMM-Newton Grant (NAG5-9982), the NASA Graduate Research Fellows Program (NGT5-50387), and the Pennsylvania Space Grant Consortium.

Lewis, K. T.; Eracleous, M.; Gliozzi, M.; Sambruna, R. M.; Mushotzky, R.

2004-08-01

72

4U 0115+63 from RXTE and INTEGRAL Data: Pulse Profile and Cyclotron Line Energy  

E-print Network

We analyze the observations of the transient X-ray pulsar 4U 0115+63 with the RXTE and INTEGRAL observatories in a wide X-ray (3-100 keV) energy band during its intense outbursts in 1999 and 2004. The energy of the fundamental harmonic of the cyclotron resonance absorption line near the maximum of the X-ray flux from the source (luminosity range 5x10^{37} - 2x10^{38} erg/s) is ~11 keV. When the pulsar luminosity falls below ~5x10^{37} erg/s, the energy of the fundamental harmonic is displaced sharply toward the high energies, up to ~16 keV. Under the assumption of a dipole magnetic field configuration, this change in cyclotron harmonic energy corresponds to a decrease in the height of the emitting region by ~2 km, while other spectral parameters, in particular, the cutoff energy, remain essentially constant. At a luminosity ~7x10^{37} erg/s, four almost equidistant cyclotron line harmonics are clearly seen in the spectrum. This suggests that either the region where the emission originates is compact or the emergent spectrum from different (in height) segments of the accretion column is uniform. We have found significant pulse profile variations with energy, luminosity, and time. In particular, we show that the profile variations from pulse to pulse are not reduced to a simple modulation of the accretion rate specified by external conditions.

S. S. Tsygankov; A. A. Lutovinov; E. M. Churazov; R. A. Sunyaev

2007-04-22

73

RXTE observations of 4U 1630-47 during the peak of its 1998 outburst  

E-print Network

We present an analysis of the RXTE observations of 4U 1630-47 during its outburst of 1998. The light curve and the spectral evolution of the outburst were distinctly different from the outbursts of the same source in 1996 and in 1999. Special emphasis of our analysis was on the observations taken during the initial rise of the flux and during the maximum of the outburst. The maximum of the outburst was divided into three plateaus, with almost constant flux within each plateau, and fast jumps between them. The spectral and timing parameters are stable for each individual plateau, but distinctly different between the plateaus. The variability detected on the first plateau is of special interest. During these observations the source exhibits quasi-regular modulations with period of ~10 - 20 s. Our analysis revealed significant differences in spectral and temporal behavior of the source at high and low fluxes during this period of time. The source behavior can be generally explained in the framework of the two-phase model of the accretion flow, involving a hot inner comptonization region and surrounding optically thick disk. The variability and spectral evolution of the source were similar to what was observed earlier for other X-ray Novae. We show that 4U 1630-47 has a variety of properties which are typical for Galactic black hole binaries, both transient and persistent. We argue that this system may be an intermediate case between different groups of black hole candidates.

Sergey P. Trudolyubov; Konstantin N. Borozdin; William C. Priedhorsky

1999-11-18

74

An Expanded RXTE Survey of Long-Term X-ray Variability in Seyfert 1 Galaxies  

NASA Technical Reports Server (NTRS)

The first seven years of RXTE monitoring of Seyfert 1 active galactic nuclei have been systematically analyzed to yield five homogenous samples of 2-12 keV light curves, probing hard X-ray variability on successively longer durations from approx. 1 day to approx. 3.5 years. 2-10 keV variability on time scales of approx. 1 day, as probed by ASCA, are included. All sources exhibit stronger X-ray variability towards longer time scales, with variability amplitudes saturating at the longest time scales, but the increase is greater for relatively higher luminosity sources. The well-documented anticorrelation between variability amplitude and luminosity is confirmed on all time scales. However, anticorrelations between variability amplitude and black hole mass estimate are evident on only the shortest time scales probed. The data are consistent with the models of power spectral density (PSD) movement described in Markowitz et al. (2003) and McHardy et al. (2004), whereby Seyfert 1 galaxies variability can be described by a single, universal PSD shape whose cutoff frequency scales with black hole mass. The best-fitting scaling relations between variability time scale, black hole mass and X-ray luminosity support an average accretion rate of 2% of the Eddington limit for the sample. Nearly all sources exhibit stronger variability in the relatively soft 2-4 keV band compared to the 7-12 keV band on all time scales. Color-flux diagrams support also Seyfert 1s' softening as they brighten. There are indications that relatively less luminous or less massive sources exhibit a greater degree of spectral variability for a given increase in overall flux.

Markowitz, A.; Edelson, R.

2004-01-01

75

RXTE Observations of an Outburst of Recurrent X-ray Nova GS 1354-644  

E-print Network

We present the results of Rossi X-ray Timing Explorer observations of GS 1354-644 during a modest outburst in 1997-1998. The source is one of a handful of black hole X-ray transients that are confirmed to be recurrent in X-rays. A 1987 outburst of the same source observed by Ginga was much brighter, and showed a high/soft spectral state. In contrast the 1997-1998 outburst showed a low/hard spectral state. Both states are typical for black hole binaries. The RXTE All Sky Monitor observed an outburst duration of 150 to 200 days. PCA and HEXTE observations covered ~70 days near the maximum of the light curve and during the flux decline. Throughout the observations, the spectrum can be approximated by Compton upscattering of soft photons by energetic electrons. The hot electron cloud has a temperature kT ~30 keV and optical depth tau~4--5. To fit the data well an additional iron fluorescent line and reflection component are required, which indicates the presence of optically thick cool material, most probably in the outer part of the accretion disk. Dramatic fast variability was observed, and has been analyzed in the context of a shot noise model. The spectrum appeared to be softest at the peaks of the shot-noise variability. The shape of the power spectrum was typical for black hole systems in a low/hard state. We note a qualitative difference in the shape of the dependence of fractional variability on energy, when we compare systems with black holes and with neutron stars. Since it is difficult to discriminate these systems on spectral grounds, at least in their low/hard states, this new difference might be important.

Mikhail G. Revnivtsev; Konstantin N. Borozdin; William C. Priedhorsky; Alexey Vikhlinin

1999-10-13

76

Results from a deep RXTE/PCA scan across the Galactic plane  

NASA Astrophysics Data System (ADS)

We present the results of deep scans across the Galactic plane that were performed with RXTE/PCA in 2010-2011. We studied the stripe from bII = 0 to bII = -30 at lII ? 18.5. We show that the variance of the cosmic X-ray background (CXB) at angular scales 1 deg2 is approximately 5 per cent, which is compatible with the variance expected from Poisson variations of a number of discrete sources within the considered field of view. We estimate the cumulative fractional emissivity of the Galactic ridge X-ray emission (GRXE) as (3.0 0.3) 1027 erg s-1 M?-1 in the energy band 2-10 keV. We do not detect significant variations of the GRXE energy spectrum over the studied latitudes, which might be expected if the GRXE consists of contributions of sources with very different characteristic ages and scaleheights. Making use of ROSAT/PSPC/R7 data, collected within the stripe of our study, we estimate the cumulative emissivity of GRXE sources in the energy band 0.5-2 keV as 8 1027 erg s-1 M?-1; however, this estimate is subject to uncertainties owing to low-accuracy correction for interstellar photo-absorption. At Galactic latitudes -12 to -18 we detect 6-8 degrees size contributionfrom the hot plasma component, with the effective temperature 1.6 keV significantly exceeding that usually known for the soft X-ray Galactic background. Its surface brightness is higher than that of any other Galactic components at energies 1-2 keV and gives up to 20 per cent of the CXB at these energies. Accounting for such emission is of vital importance, for example, in studies of the emission of clusters of galaxies at their virial radii.

Revnivtsev, Mikhail G.; Molkov, Sergey V.

2012-08-01

77

Excited Delirium  

PubMed Central

Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

2011-01-01

78

Food Science.  

ERIC Educational Resources Information Center

Presents food science experiments designed for high school science classes that aim at getting students excited about science and providing them with real-life applications. Enables students to see the application of chemistry, microbiology, engineering, and other basic and applied sciences to the production, processing, preservation, evaluation,

Barkman, Susan J.

1996-01-01

79

RXTE all-sky slew survey. Catalog of X-ray sources at |b|>10o  

NASA Astrophysics Data System (ADS)

We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (|b|>10o) survey based on RXTE/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4? limiting flux of ? 1.8 (2.5) 10-11 erg s-1 cm-2 in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands is similar to and an order of magnitude higher than that of the previously record HEAO-1 A1 and HEAO-1 A4 all-sky surveys, respectively. A combined 7 103 sq deg area of the sky is sampled to flux levels below 10-11 erg s-1 cm-2 (3-20 keV). In total 294 sources are detected and localized to better than 1 deg. 236 (80%) of these can be confidently associated with a known astrophysical object; another 22 likely result from the superposition of 2 or 3 closely located known sources. 35 detected sources remain unidentified, although for 12 of these we report a likely soft X-ray counterpart from the ROSAT all-sky survey bright source catalog. Of the reliably identified sources, 63 have local origin (Milky Way, LMC or SMC), 64 are clusters of galaxies and 100 are active galactic nuclei (AGN). The fact that the unidentified X-ray sources have hard spectra suggests that the majority of them are AGN, including highly obscured ones (NH>1023 cm-2). For the first time we present a log N-log S diagram for extragalactic sources above 4 10-12 erg s-1 cm-2 at 8-20 keV. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/927

Revnivtsev, M.; Sazonov, S.; Jahoda, K.; Gilfanov, M.

2004-05-01

80

RXTE Observation of 4U 1630-47 During its 1998 Outburst  

NASA Technical Reports Server (NTRS)

During the 1998 outburst of 4U 1630-47 it was extensively observed with the Rossi X-ray Timing Explorer (RXTE). In order to cover the outburst more thoroughly our data (Obs. ID: 30178-0[1-2]- ) were combined with those of Cui et al. (Obs. ID: 30188-02-). These observations were later compared with the complementary observations. Power density and energy spectra have been made for each observation. The data was used to place radio and hard X-ray observations within context. Analysis of SAX (Satellite per Astronomia a raggi X) and BATSE (Burst and Transient Source Experiment) data was also included within the study. The count rate and position in hardness-intensity, color-color diagrams and simple spectral fits are used to track the concurrent spectral changes. The source showed seven distinct types of timing behavior, most of which show differences with the canonical black hole spectral/timing states. In marked contrast to previous outbursts, we find quasi-periodic oscillation (QPO) signals during nearly all stages of the outburst with frequencies between 0.06 Hz and 14 Hz and a remarkable variety of other characteristics. In particular we find large (up to 23% rms) amplitude QPO on the early rise. Later, slow 0.1 Hz semi- regular short (- 5 sec), 9 to 16% deep dips dominate the light curve. At this time there are two QPOS, one stable near 13.5 Hz and the other whose frequency drops from 6-8 Hz to - 4.5 Hz during the dips. BeppoSAX observations during the very late declining phase show 4U 1630-47 in a low state. These results will shortly be published. We are completing a detailed analysis of the energy spectra (in preparation). The QPO/noise properties are being correlated with the concurrent spectral changes. Detailed studies of the QPO are being undertaken using sophisticated timing analysis methods. Finally a comparison with the other outbursts of 1630-47 is being made.

Dieters, Stefan W.

1999-01-01

81

RXTE and BeppoSAX Observations of MCG-5-23-16: Reflection From Distant Cold Material  

NASA Technical Reports Server (NTRS)

We examine the spectral variability of the Seyfert 1.9 galaxy MCG-5-23-16 using RXTE and BeppoSAX observations spanning 2 years from April 1996 to April 1998. During the first year the X-ray source brightens by a factor of approximately 25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time of between approximately 1 light day and approximately 1.5 light years. This corresponds to a distance of 0.001 pc to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10(exp 15) cm and 1.6 x 10(exp l8) cm from the X-ray source. In other words, the reprocessing in MCG-5-23-16 is not dominated by the inner regions of a standard accretion disk.

Mattson, B. J.; Weaver, K. A.

2003-01-01

82

Experience Gained From Launch and Early Orbit Support of the Rossi X-Ray Timing Explorer (RXTE)  

NASA Technical Reports Server (NTRS)

this paper reports the results to date of early mission support provided by the personnel of the Goddard Space Flight Center Flight Dynamics Division (FDD) for the Rossi X-Ray Timing Explorer (RXTE) spacecraft. For this mission, the FDD supports onboard attitude determination and ephemeris propagation by supplying ground-based orbit and attitude solutions and calibration results. The first phase of that support was to provide launch window analyses. As the launch window was determined, acquisition attitudes were calculated and calibration slews were planned. postlaunch, these slews provided the basis for ground determined calibration. Ground determined calibration results are used to improve the accuracy of onboard solutions. The FDD is applying new calibration tools designed to facilitate use of the simultaneous, high-accuracy star observations from the two RXTE star trackers for ground attitude determination and calibration. An evaluation of the performance of these tools is presented. The FDD provides updates to the onboard star catalog based on preflight analysis and analysis of flight data. The in-flight results of the mission support in each area are summarized and compared with pre-mission expectations.

Fink, D. R.; Chapman, K. B.; Davis, W. S.; Hashmall, J. A.; Shulman, S. E.; Underwood, S. C.; Zsoldos, J. M.; Harman, R. R.

1996-01-01

83

Chandra and RXTE Observations of 1E 1547.0-5408: Comparing the 2008 and 2009 Outbursts  

NASA Technical Reports Server (NTRS)

We present results from observations of the magnetar 1E 1547.0-5408 (SGR J1550-5418) taken with the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer (RXTE) following the source s outbursts in 2008 October and 2009 January. During the time span of the Chandra observations, which covers days 4 through 23 and days 2 through 16 after the 2008 and 2009 events, respectively, the source spectral shape over the Chandraband remained stable, while the pulsar s spindown rate in the same span in 2008 increased by a factor of 2.2 as measured by RXTE. This suggests decoupling between the source s spin-down and radiative changes, hence between the spin-down-inferred magnetic field strength and that inferred spectrally. The lack of spectral variation during flux decay is surprising for models of magnetar outbursts. We also found a strong anti-correlation between the phase-averaged flux and the pulsed fraction in the 2008 and 2009 Chandra data, but not in the pre-2008 measurements. We discuss these results in the context of the magnetar model.

Ng, C.-Y.; Kaspi, V. M.; Dib, R.; Olausen, S. A.; Scholz, P.; Guever, T.; Oezel, F.; Gavril, F. P.; Woods, P. M.

2010-01-01

84

RXTE Observations of the 1A 1118-61 in an Outburst, and the Discovery of a Cyclotron Line  

NASA Technical Reports Server (NTRS)

We present the analysis of RXTE monitoring data obtained during the January 2009 outburst of the hard X-ray transient IA 1118-61. Using these observations the broadband (3.5-120 keV) spectrum of the source was measured for the first time ever. We have found that the broadband continuum spectrum of the source is similar to other accreting pulsars and is well described by several conventionally used phenomenological models. We have discovered that regardless of the applied continuum model, a prominent broad absorption feature at approx. 55 keV is observed. We interpret this feature as a Cyclotron Resonance Scattering Feature (CRSF). The observed CRSF energy is one of the highest known and corresponds to a magnetic field of B approx. 4.8 x 10(exp 12) G in the scattering region. Furthermore, our data suggests an iron emission line presence, which was not reported previously for lA 1118-61 as well. Timing properties of the source, including a strong spin-up, were found to be similar to those observed by CGRO/BATSE during the previous outburst, however the broadband capabilities of RXTE reveal a more complicated energy dependency of the pulse-profile.

Doroshenko, V.; Suchy, S.; Santangelo, A; Staubert, R.; Kreykenbohm, I.; Rothschild, R.; Pottschmidt, K.; Wilms, J.

2010-01-01

85

Multi-photon excitation microscopy  

Microsoft Academic Search

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase

Alberto Diaspro; Paolo Bianchini; Giuseppe Vicidomini; Mario Faretta; Paola Ramoino; Cesare Usai

2006-01-01

86

Disk-dominated States of 4U 1957+11: Chandra, XMM-Newton, and RXTE Observations of Ostensibly the Most Rapidly Spinning Galactic Black Hole  

E-print Network

We present simultaneous Chandra High-Energy Transmission Gratings (HETG) and Rossi X-ray Timing Explorer (RXTE) observations of a "soft state" of the black hole candidate 4U 1957+11. These spectra, having limited hard X-ray ...

Nowak, Michael A.

87

Low-Luminosity States of the Black Hole Candidate GX 339-4. I. ASCA and Simultaneous Radio/RXTE Observations  

NASA Astrophysics Data System (ADS)

We discuss a series of observations of the black hole candidate GX 339-4 in low-luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-Ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 MHz and 8.3-9.1 GHz radio observations. All of these observations have (3-9 keV) flux <~10-9 ergs s-1 cm-2. The ASCA data show evidence for an ~6.4 keV Fe line with equivalent width ~40 eV, as well as evidence for a soft excess that is well modeled by a power law plus a multicolor blackbody spectrum with peak temperature ~150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths ~20-140 eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. ``Sphere+disk'' Comptonization models and advection-dominated accretion flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of ?~3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of size greater than \\Oscr(107GM/c2).

Wilms, Jrn; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; Di Matteo, Tiziana

1999-09-01

88

A Study of the New X-ray Transient RXTE J2123-058 during its Post-Outburst State  

E-print Network

We carried out I, R, V and B photometric observations of the neutron star X-ray binary RXTE J2123-058 shortly after the end of the X-ray outburst in mid-1998. We adopt the low mass binary model to interpret our observations. After folding our data on the 0.24821-d orbital period, and correcting for the steady brightness decline following the outburst, we observe sinusoidal oscillations with hints of ellipsoidal modulations which became progressively more evident. Our data also show that the decline in brightness was faster in the V band than in the R and I bands. This suggests both the cooling of an irradiation-heated secondary star and the fading of an accretion disc over the nights of our observations.

Roberto Soria; Kinwah Wu; Duncan Galloway

1999-06-16

89

A Second Look at the Accretion Disk Wind in GRS 1915+015 as Observed with Chandra and RXTE  

NASA Astrophysics Data System (ADS)

We present a re-analysis of simultaneous Chandra and RXTE observations of the microquasar GRS 1915+015 observed in a soft state first presented by Ueda et al. (2009). In our extended analysis, we incorporate a number of previously unpublished highly ionized absorption lines above 7.5 keV, as well as self-consistent relativistic reflection models, updated ISM cross-sections, and detailed XSTAR photoionization models for a self-consistent treatment of the continuum and the accretion disk wind. Through a time-resolved spectral analysis, we confirm and tightly constrain the ionization parameter and column density variability of the wind during the observations. We discuss properties of the wind, including its evolution and mass loss rate, and the relationship between accretion, ejection, and ionization processes revealed by our updated modeling.

Keck, Mason; Neilsen, Joseph

2015-01-01

90

Modeling Reflection Signatures in the RXTE Spectra from X-ray Binaries: The GX 339-4 Case  

NASA Astrophysics Data System (ADS)

Despite its limited spectral resolution, the RXTE mission has provided a vast amount of observational data for many X-ray sources over its entire lifespan of 16 years. We have started a camping to analyze all the available data for most X-ray binaries, focusing on the detection and modeling of reflection signatures. We present the results of this camping on the analysis of all available data for GX 339-4 in the hard state. Strong reflection features such as the Fe K emission line, the Fe K-edge, and the Compton hump are clearly observed on a wide range of luminosities. By fitting the spectra with the most advanced relativistic reflection models we are to impose constrains on the ionization state of the gas, the inner radius of the accretion disk, and the inclination of the system. A novel technique to improve the quality of PCA spectral data will also be discussed.

Garcia, Javier; McClintock, Jeffrey E.; Steiner, James F.; Remillard, Ronald A.; Grinberg, Victoria

2014-08-01

91

The Nature of the X-Ray Binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift Observations  

NASA Technical Reports Server (NTRS)

We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+ 1816. The Swift/XRT data allow us to refine the position of the source to R.A. (J2000) = 19h 29m 55.9s, Decl. (J2000) = +18 deg 18 feet 38 inches . 4 (+/- 3 inches .5), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard (Gamma approx 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsations at 12.43781 (+/- 0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+ 1816 being an high-mass X-ray binary (HMXB) with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implication of IGR J19294+1816 being an Supergiant Fast X-ray Transient (SFXT).

Rodriquez, J.; Tomsick, J. A.; Bodaghee, A.; ZuritaHeras, J.-A.; Chaty, S.; Paizis, A.; Corbel, S.

2009-01-01

92

Comprehensive Analysis of RXTE Data from Cyg X-1. Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations  

NASA Technical Reports Server (NTRS)

We present timing and spectral analysis of approx. 2.2 Ms of Rossi X-ray Time Explorer (RXTE) archival data from Cyg X-1. Using the generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral power-law index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index- QPO frequency correlation shows a saturation of the photon index Gamma approx. 2.1 at high values of the low frequency upsilon(sub L). The saturation level of Gamma approx. 2.1 is the lowest value found yet in BHCs. The bolometric luminosity does not show clear correlation with the index. We also show that Fe K(sub alpha) emission line strength (equivalent width, EW) correlates with the QPO frequency. EW increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state. The revealed observational correlations allow us to propose a scenario for the spectral transition and iron line formation which occur in BHC sources. We also present the spectral state (the power-law index) evolution for eight years of Cyg X-1 observations by RXTE.

Shaposhnikov, Nickolai; Titarchuk, Lev

2006-01-01

93

Millisecond dip events in the 2007 RXTE/PCA data of Sco X-1 and the TNO size distribution  

E-print Network

Millisecond dips in the RXTE/PCA archival data of Sco X-1 taken from 1996 to 2002 were reported recently. Those dips were found to be most likely caused by instrumental dead time but may also contain some true astronomical events, which were interpreted as the occultation of X-rays from Sco X-1 by Trans-Neptunian Objects (TNO) of 100-m size. Here we report the results of search for millisecond dip events with the new RXTE/PCA data of Sco X-1 taken in year 2007. Adopting the same selection criteria as that in the previous study, we found only 3 dip events in 72-ks data, much fewer than the 107 events found in the 560-ks data taken from 1996 to 2002 reported earlier. The new data provides more detailed information of individual `very large events' (VLEs), which is not available in the old archival data. Although the number of VLEs does not obviously increase during the occurrence of dip events, all the 3 dip events are coincident in time with VLEs that have no flags set for any of the propane or the 6 main xenon anodes. It is a strong indication of instrumental effects. No significant dips which might be real occultation by 60 -- 100 m TNOs were observed. With only 72-ks data, however, the previously proposed possibility that about 10 percent of the dip events might not be instrumental still cannot be strictly excluded. Using the absence of those anomalous VLEs as the criterion for identifying non-instrumental dip events, we found, at a lower confidence level, 4 dip events of duration 8 - 10 ms in the 72-ks data. Upper limits to the size distribution of TNOs at the small size end are suggested.

Chih-Yuan Liu; Hsiang-Kuang Chang; Jau-Shian Liang; Sun-Kun King

2008-05-12

94

Attention STEM Teachers! Learn some exciting, simple, low-cost  

E-print Network

be integrated into your existing lesson plans. Why: To engage and excite young people in science and math! ogram, physics, math and technology teachers; middle school science teachers What: A one-week workshop to show

Hochberg, Michael

95

J. Chem. Sci. Vol. 123, No. 3, May 2011, pp. 265277. c Indian Academy of Sciences. Excited state charge transfer reaction in (mixed solvent + electrolyte)  

E-print Network

charge transfer reaction in (mixed solvent + electrolyte) systems: Role of reactantsolvent and reactant Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata, 700 098 intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in two sets of mixed solvents, (1

Biswas, Ranjit

96

Double Excitations of Helium  

NASA Astrophysics Data System (ADS)

The double excitations of helium offer an ideal case for investigating electron dynamics in a three-body system. Our study of the He ^1P^o double excitations comprises measurements of the partial photoionization cross sections ?n (He^+) and the partial photoelectron angular distribution parameters ?n for the series N(K,T)^Ai up to the N=5 threshold. The experiment was performed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 10^12 photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K=N-2 are clearly delineated in both ?n and ?_n. The ?n show all minor series with N=K-4 very clearly, in contrast to measurements of the total absorption cross section, as well as very weak members with A=-1. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N=5 and N=6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He^+(n), whereas the peak-to-valley variation in the ?n within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the ?n and ?n of the photoelectron satellites are virtually identical provided the final ionic state He^+(n), n >= 2, is reached via an excited series N with ?=1, or ?=2, where ?=N-n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (N-K), A, and T. We tentatively propose an extension of these systematics for higher series N >= 5, although further theoretical work toward understanding these features of the doubly excited states will be needed. The experiment was performed in close collaboration with C.D. Caldwell, M.O. Krause, S.P. Frigo, and S.B. Whitfield. Valuable theoretical contributions were made by J.-Z. Tang and I. Shimamura. Part of the work appeared in Phys. Rev. Lett. 75, 1479 (1995). This work is supported by the National Science Foundation under grants PHY-9207634 and PHY-9507573.

Menzel, Alexander

1996-05-01

97

Sharing the excitement of deep ocean research The UK has long prided itself on its achievements in science, engineering and technology. They contribute  

E-print Network

in science, engineering and technology. They contribute directly to the country's prosperity and benefit of the world's deepest oceans, or understanding the forces behind glaciers and volcanoes. They are involved

Anderson, Jim

98

Launch Excitement with Water Rockets  

NSDL National Science Digital Library

Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable launchers and rockets for experiments while learning fundamental principles of physics.

John Penick

2007-10-01

99

The Physical Interpretation of X-Ray Phase Lags and Coherence: RXTE Observations of Cygnus X-1 as a Case Study  

NASA Technical Reports Server (NTRS)

There have been a number of recent spectral models that have been successful in reproducing the observed X-ray spectra of galactic black hole candidates (GBHC). However, there still exists controversy over such issues as: what are the sources of hard radiation, what is the system's geometry, is the accretion efficient or inefficient, etc. A potentially powerful tool for distinguishing among these possibilities, made possible by the Rossi X-ray Timing Explorer (RXTE), is the variability data, especially the observed phase lags and variability coherence. These data, in conjunction with spectral modeling, have the potential of determining physical sizes of the system, as well as placing strong constraints on both Compton corona and advection models. As an example, we present RXTE variability data of Cygnus X-1.

Nowak, M. A.; Dove, J. B.; Vaughan, B. A.; Wilms, J.; Begelman, M. C.

1998-01-01

100

Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-Ray Observations of NGC 4945  

NASA Technical Reports Server (NTRS)

NGC 4945 is one of the brightest Se.yfert galaxies on the sky at 100 keV, but is completely absorbed below 10 keV, implying an optical depth of the absorber to electron scattering of a few; its absorption column is probably the largest which still allows a direct view of the nucleus at hard X-ray energies. Our observations of it with the Rossi X-ray Timing Explorer (RXTE) satellite confirm the large absorption, which for a simple phenomenological fit using an absorber with Solar abundances implies a column of 4.5(sup 0.4, sub -0.4) x 10(exp 24) /sq cm. Using a a more realistic scenario (requiring Monte Carlo modeling of the scattering), we infer the optical depth to Thomson scattering of approximately 2.4. If such a scattering medium were to subtend a large solid angle from the nucleus, it should smear out any intrinsic hard X-ray variability on time scales shorter than the light travel time through it. The rapid (with a time scale of approximately a day) hard X-ray variability of NGC 4945 we observed with the RXTE implies that the bulk of the extreme absorption in this object does not originate in a parsec-size, geometrically thick molecular torus. Limits on the amount of scattered flux require that the optically thick material on parsec scales must be rather geometrically thin, subtending a half-angle < 10 deg. This is only marginally consistent with the recent determinations of the obscuring column in hard X-rays, where only a quarter of Seyfert 2s have columns which are optically thick, and presents a problem in accounting for the Cosmic X-ray Background primarily with AGN possessing the geometry as that inferred by us. The small solid angle of the obscuring material, together with the black hole mass (of approximately 1.4 x 10(exp 6) solar mass) from megamaser measurements. allows a robust determination of the source luminosity, which in turn implies that the source radiates at approximately 10% of the Eddington limit.

Madejski, G.; Zycki, P.; Done, C.; Valinia, A.; Blanco, P.; Rothschild, R.; Turek, B.

2000-01-01

101

Science Fact, Science Fiction 16 23 March 2013  

E-print Network

Science Fact, Science Fiction 16 ­ 23 March 2013 Discover, celebrate and be part of science. This year's theme, Science Fact, Science Fiction, provides an exciting opportunity to address how science is portrayed in works of fiction and to debunk popular science myths. Royal Holloway co-ordinates a broad

Royal Holloway, University of London

102

Eclipse Timings of the Low Mass X-ray Binary EXO0748-676 III. An Apparent Orbital Period Glitch Observed with USA and RXTE  

E-print Network

We present 7 eclipse timings of the low mass X-ray binary EXO0748-676 obtained with the USA experiment during 1999-2000 as well as 122 eclipse timings obtained with RXTE during 1996-2000. According to our analysis, the mean orbital period has increased by ~8 ms between the pre-RXTE era (1985-1990) and the RXTE/USA era (1996-2000). This corresponds to an orbital period derivative of P(orb)/(dP(orb)/dt)~2x10^7 years. However, neither a constant orbital period derivative nor any other simple ephemeris provides an acceptable fit to the data: individual timings of eclipse centers have residuals of up to 15 or more seconds away from our derived smooth ephemerides. When we consider all published eclipse timing data including those presented here, a model that includes observational measurement error, cumulative period jitter, and underlying period evolution is found to be consistent with the timing data. We discuss several physical mechanisms for LMXB orbital evolution in an effort to account for the change in orbital period and the observed intrinsic jitter in the mid-eclipse times.

M. T. Wolff; P. Hertz; K. S. Wood; P. S. Ray; R. M. Bandyopadhyay

2002-05-02

103

The discovery outburst of the X-ray transient IGR J17497-2821 observed with RXTE and ATCA  

E-print Network

We report the results of a series of RXTE and ATCA observations of the recently-discovered X-ray transient IGR J17497-2821. Our 3-200 keV PCA+HEXTE spectral analysis shows very little variations over a period of ~10 days around the maximum of the outburst. IGR J17497-2821 is found in a typical Low Hard State (LHS) of X-ray binaries (XRB), well represented by an absorbed Comptonized spectrum with an iron edge at about 7 keV. The high value of the absorption (~4 e22 cm-2) suggests that the source is located at a large distance, either close to the Galactic center or beyond. The timing analysis shows no particular features, while the shape of the power density spectra is also typical of LHS of XRBs, with ~36% RMS variability. No radio counterpart is found down to a limit of 0.21 mJy at 4.80 GHz and 8.64 GHz. Although the position of IGR J17497-2821 in the radio to X-ray flux diagram is well below the correlation usually observed in the LHS of black holes, the comparison of its X-ray properties with those of other sources leads us to suggest that it is a black hole candidate.

Jerome Rodriguez; Marion Cadolle Bel; John A. Tomsick; Stephane Corbel; Catherine Brocksopp; Ada Paizis; Simon E. Shaw Arash Bodaghee

2006-12-14

104

Monitoring the Violent Activity from the Inner Accretion Disk of the Seyfert 1.9 Galaxy NGC 2992 with RXTE  

NASA Technical Reports Server (NTRS)

We present the results of a one year monitoring campaign of the Seyfert 1.9 galaxy NGC 2992 with RXTE. Historically, the source has been shown to vary dramatically in 2-10 keV flux over timescales of years and was thought to be slowly transitioning between periods of quiescence and active accretion. Our results show that in one year the source continuum flux covered almost the entire historical range, making it unlikely that the low-luminosity states correspond to the accretion mechanism switching off. During flaring episodes we found that a highly redshifted Fe K line appears, implying that the violent activity is occurring in the inner accretion disk, within 100 gravitational radii of the central black hole. We also found that the Compton y parameter for the X-ray continuum remained approximately constant during the large amplitude variability. These observations make NGC 2992 well-suited for future multi-waveband monitoring, as a test-bed for constraining accretion models.

Mruphy, Kendrah D.; Yaqoob, Tahir; Terashima, Yuichi

2007-01-01

105

TeV and X-ray Monitoring of LS I +61 303 With VERITAS, Swift, and RXTE  

E-print Network

Between September 2006 and February 2007, the galactic binary LS I +61 303 was monitored in the TeV band with the VERITAS array of imaging Cherenkov telescopes. These observations confirm LS I +61 303 as a variable TeV gamma-ray source, with emission peaking between orbital phase 0.6 and 0.7. During this observational period, monitoring in the X-ray regime was also carried out using both the RXTE and Swift detectors, which offered complementary coverage of the source. Outbursts in the 0.2-10 keV band were observed by both satellites at close to the same orbital phase as the TeV peak during the 2 orbital cycles covered simultaneously in both bands. While this source has been extensively studied in the X-ray band in the past, this is the first observational campaign to utilize contemporaneous X-ray and TeV data on LS I +61 303.

VERITAS Collaboration; A. Smith

2007-09-27

106

Science.  

ERIC Educational Resources Information Center

This document contains the following papers on science instruction and technology: "A 3-D Journey in Space: A New Visual Cognitive Adventure" (Yoav Yair, Rachel Mintz, and Shai Litvak); "Using Collaborative Inquiry and Interactive Technologies in an Environmental Science Project for Middle School Teachers: A Description and Analysis" (Patricia

Roach, Linda E., Ed.

107

Science  

NSDL National Science Digital Library

Science Magazine online. Access abstracts and full text articles updated weekly. Browse through the current issue or archived articles. Obtain information on magazine subscriptions and student, educator, and scientist awards. A wealth of science information is at your fingertips in all disciplines, particularly medicine. Links to other AAAS resources including extensive career information and the latest in HIV/AIDS and aging research.

108

Continuously excited laser  

Microsoft Academic Search

There is disclosed continuously-excited lasers of the CO mixing, and supersonic CO, types. There is specifically disclosed a method, and a laser apparatus, for producing a repetitively pulsed output, in which a stream of excited gas, of the type having a relatively long excitation life, is produced, stored and subsequently transferred, in the form of pulses, to a power extraction

R. C. McLeary; P. J. Beckwith

1984-01-01

109

Montana State University 1 Computer Science  

E-print Network

Montana State University 1 Computer Science A computer science degree is highly curriculum is designed with considerable flexibility, due to the numerous types of computer science jobs. Students may then select from exciting computer science electives such as artificial intelligence

Maxwell, Bruce D.

110

ALGEBRA SEMINAR TALK Department of Computer Science  

E-print Network

ALGEBRA SEMINAR TALK WITH LILA KARI Department of Computer Science The University of Western for Theoretical Computer Science" Abstract: We are now witnessing exciting interactions between computer science absorbing notions, techniques and methodologies intrinsic to computer science and mathematics, theoretical

Sinnamon, Gordon J.

111

A Simultaneous RXTE and XMM-Newton Observation of the Broad-Line Radio Galaxy 3C 111  

NASA Astrophysics Data System (ADS)

We present the results of simultaneous XMM-Newton and RXTE observations of the broad-line radio galaxy 3C 111. We find that the Compton reflection bump is extremely weak; however, broad residuals are clearly present in the spectrum near the Fe K? emission line region. When fitted with a Gaussian emission line, the feature has an equivalent width of 40-100 eV and FWHM of greater than 20,000 km s-1 however, the exact properties of this weak line are highly dependent on the chosen continuum model. The width of the line suggests an origin in the inner accretion disk, which is, however, inconsistent with the lack of Compton reflection. We find that much of the broad residual emission can be attributed to continuum curvature. The data are consistent with a model in which the primary power-law continuum is reprocessed by an accretion disk that is truncated at small radii. Alternatively, the primary source could be partially covered by a dense absorber. The latter model is less attractive than the former because of the small inclination angle of the jet of 3C 111 to the line of sight. We consider it likely that the curved continuum of the partial covering model is fortuitously similar to the continuum shape of the reprocessing model. In both models, the fit is greatly improved by the addition of an unresolved Fe K? emission line, which could arise in either a Compton-thin obscuring torus or dense clouds lying along the line of sight. We also find that there are unacceptable residuals at low energies in the MOS data in particular, which were modeled as a Gaussian with an energy of ~1.5 keV; we attribute these residuals to calibration uncertainties of the MOS detectors.

Lewis, Karen T.; Eracleous, Michael; Gliozzi, Mario; Sambruna, Rita M.; Mushotzky, Richard F.

2005-04-01

112

Science Bulletins  

NSDL National Science Digital Library

The American Museum of Natural History presents Science Bulletins, an innovative online and exhibition program that offers the public a window into the excitement of scientific discovery. Science Bulletins is a video program that brings you the latest developments in the fields of astrophysics, Earth science, biodiversity and human biology and evolution through documentary feature stories about scientists in the field and regular brief research updates using scientific visualizations and imagery. On this web site, Science Bulletins presents current videos and provides an archive of past stories, all with resource links, as well as educator resources and a guide for educators interested in using Science Bulletins in the classroom.

113

Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance  

NASA Technical Reports Server (NTRS)

We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

2010-01-01

114

DISCOVERY AND MONITORING OF A NEW BLACK HOLE CANDIDATE XTE J1752-223 WITH RXTE: RMS SPECTRUM EVOLUTION, BLACK HOLE MASS, AND THE SOURCE DISTANCE  

SciTech Connect

We report on the discovery and monitoring observations of a new galactic black hole (BH) candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on 2009 October 21 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/high-soft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass BH binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a blackbody spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (rms) variability in the RXTE/PCA energy band with the source spectral state and conclude that broadband variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition, and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hard-to-soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source of about 3.5 kpc.

Shaposhnikov, Nikolai [Department of Astronomy, CRESST/University of Maryland, College Park, MD 20742 (United States); Markwardt, Craig; Swank, Jean; Krimm, Hans, E-mail: nikolai.v.shaposhnikov@nasa.go [Goddard Space Flight Center, NASA, Astrophysics Science Division, Greenbelt MD 20771 (United States)

2010-11-10

115

Millisecond dips in the 2007-09 RXTE/PCA light curve of Sco X-1 and one possible occultation event  

NASA Astrophysics Data System (ADS)

Serendipitous stellar occultation search is so far the only way to detect the existence of very small, very dim, remote objects in the Solar system. To date, however, there are only very few reported detections for trans-Neptunian objects (TNOs) in optical bands. In the X-ray band, with the RXTE/PCA data of Sco X-1 taken from 2007 June to 2009 October, we found one possible X-ray occultation event. We discuss the veracity and properties of this event, and suggest upper limits to the size distribution of TNOs at hectometre size and of main-belt asteroids at decametre size.

Chang, Hsiang-Kuang; Liu, Chih-Yuan; Chen, Kuan-Ting

2011-02-01

116

Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State  

NASA Technical Reports Server (NTRS)

Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

2009-01-01

117

RXTE All-Sky Slew Survey. Catalog of X-Ray Sources at B Greater Than 10 deg  

NASA Technical Reports Server (NTRS)

We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (absolute value of b greater than l0 deg.) survey based on RXTE/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4(sigma) limiting flux of approx. = 1.8 (2.5) x 10(exp -l1) erg/s sq cm in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands is similar to and an order of magnitude higher than that of the previously record HEAO-1 A1 and HEAO-1 A4 all-sky surveys, respectively. A combined 7 x 10(exp 3) sq. deg area of the sky is sampled to flux levels below l0(exp -11) erg/ s sq cm (3-20 keV). In total 294 sources are detected and localized to better than 1 deg. 236 (80%) of these can be confidently associated with a known astrophysical object; another 22 likely result from the superposition of 2 or 3 closely located known sources. 35 detected sources remain unidentified, although for 12 of these we report a likely soft X-ray counterpart from the ROSAT all-sky survey bright source catalog. Of the reliably identified sources, 63 have local origin (Milky Way, LMC or SMC), 64 are clusters of galaxies and 100 are active galactic nuclei (AGN). The fact that the unidentified X-ray sources have hard spectra suggests that the majority of them are AGN, including highly obscured ones (N(sub H) greater than l0(exp 23)/sq cm). For the first time we present a log N-log S diagram for extragalactic sources above 4 x l0(exp -12) erg/ s sq cm at 8-20 keV. Key words. cosmo1ogy:observations - diffuse radiation - X-rays general

Revnivtsev, M.; Sazonov, S.; Jahoda, K.; Gilfanov, M.

2004-01-01

118

RXTE Observation of Cygnus X-1: III. Implications for Compton Corona and ADAF Models. Report 3; Implications for Compton Corona and ADAF Models  

NASA Technical Reports Server (NTRS)

We have recently shown that a 'sphere + disk' geometry Compton corona model provides a good description of Rossi X-ray Timing Explorer (RXTE) observations of the hard/low state of Cygnus X-1. Separately, we have analyzed the temporal data provided by RXTE. In this paper we consider the implications of this timing analysis for our best-fit 'sphere + disk' Comptonization models. We focus our attention on the observed Fourier frequency-dependent time delays between hard and soft photons. We consider whether the observed time delays are: created in the disk but are merely reprocessed by the corona; created by differences between the hard and soft photon diffusion times in coronae with extremely large radii; or are due to 'propagation' of disturbances through the corona. We find that the time delays are most likely created directly within the corona; however, it is currently uncertain which specific model is the most likely explanation. Models that posit a large coronal radius [or equivalently, a large Advection Dominated Accretion Flow (ADAF) region] do not fully address all the details of the observed spectrum. The Compton corona models that do address the full spectrum do not contain dynamical information. We show, however, that simple phenomenological propagation models for the observed time delays for these latter models imply extremely slow characteristic propagation speeds within the coronal region.

Nowak, Michael A.; Wilms, Joern; Vaughan, Brian A.; Dove, James B.; Begelman, Mitchell C.

1999-01-01

119

Swift/BAT and RXTE Observations of the Peculiar X-ray Binary 4U 2206+54 - Disappearance of the 9.6 Day Modulation  

NASA Technical Reports Server (NTRS)

Observations of the high-mass X-ray binary 4U 2206+54 with the Swift Burst Alert Telescope (BAT) do not show modulation at the previously reported period of 9.6 days found from observations made with the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Instead, the strongest peak in the power spectrum of the BAT light curve occurs at a period of 19.25+/-0.08 days, twice the period found with the RXTE ASM. The maximum of the folded BAT light curve is also delayed compared to the maximum of the folded ASM light curve. The most recent ASM data folded on twice the 9.6 day period show 'similar morphology to the folded BAT light curve. This suggests that the apparent period doubling is a recent secular change rather than an energy-dependent effect. The 9.6 day period is thus not a permanent strong feature of the light curve. We suggest that the orbital period of 4U 2206+54 may be twice the previously proposed value.

Corbet, R. H. D.; Markwardt, C.; Tueller, J.

2007-01-01

120

Revisit to the RXTE and ASCA Data for GRO J1655-40: Effects of Radiative Transfer in Corona and Color Hardening in the Disk  

NASA Technical Reports Server (NTRS)

The results of spectral modeling of the data for a series of RXTE observations and four ASCA observations of GRO J1655-40 are presented. The thermal Comptonization model is used instead of the power-law model for the hard component of the two-component continuum spectra. The previously reported dramatic variations of the apparent inner disk radius of GRO J1655-40 during its outburst may be due to the inverse Compton scattering in the hot corona. A procedure is developed for making the radiative transfer correction to the fitting parameters from RXTE data and a more stable inner disk radius is obtained. A practical process of determining the color correction (hardening) factor from observational data is proposed and applied to the four ASCA observations of GRO J1655-40. We found that the color correction factor may vary significantly between different observations and the finally corrected physical inner disk radius remains reasonably stable over a large range of luminosity and spectral states.

Zhang, S. Nan; Zhang, Xiaoling; Wu, Xuebing; Yao, Yangsen; Sun, Xuejun; Xu, Haiguang; Cui, Wei; Chen, Wan; Harmon, B. A.; Robinson, C. R.

1999-01-01

121

Outburst of LS V +44 17 Observed by MAXI and RXTE, and Discovery of a Dip Structure in the Pulse Profile  

NASA Astrophysics Data System (ADS)

We report on the first observation of an X-ray outburst of a Be/X-ray binary pulsar, LS V +44 17/ RX J0440.9+4431, and the discovery of an absorption dip structure in the pulse profile. An outburst of this source was discovered by MAXI GSC in 2010 April. It was the first detection of transient activity of LS V +44 17 since the source was identified as a Be/X-ray binary in 1997. From the data of a follow-up RXTE observation near the peak of the outburst, we found a narrow dip structure in its pulse profile, which was clearer in the lower-energy bands. The pulse-phase-averaged energy spectra in the 3-100 keV band could be fitted with a continuum model containing a power-law function with an exponential cutoff and a blackbody component, which are modified at low energy by an absorption component. A weak iron K? emission line was also detected in the spectra. From the pulse-phase-resolved spectroscopy we found that the absorption column density at the dip phase was much higher than those in the other phases. The dip was not seen in subsequent RXTE observations at lower flux levels. These results suggest that the dip in the pulse profile originates from the eclipse of the radiation from the neutron star by the accretion column.

Usui, Ryuichi; Morii, Mikio; Kawai, Nobuyuki; Yamamoto, Takayuki; Mihara, Tatehiro; Sugizaki, Mutsumi; Matsuoka, Masaru; Hiroi, Kazuo; Ishikawa, Masaki; Isobe, Naoki; Kimura, Masashi; Kitayama, Hiroki; Kohama, Mitsuhiro; Matsumura, Takanori; Nakahira, Satoshi; Nakajima, Motoki; Negoro, Hitoshi; Serino, Motoko; Shidatsu, Megumi; Sootome, Tetsuya; Sugimori, Kousuke; Suwa, Fumitoshi; Toizumi, Takahiro; Tomida, Hiroshi; Tsuboi, Yoko; Tsunemi, Hiroshi; Ueda, Yoshihiro; Ueno, Shiro; Yamaoka, Kazutaka; Yamazaki, Kyohei; Yoshida, Atsumasa

2012-08-01

122

NASA and Mary J. Blige Encourage Exciting Careers For Women - Duration: 0:43.  

NASA Video Gallery

NASA is collaborating with award-winning recording artist Mary J. Blige to encourage young women to pursue exciting experiences and career choices through studying science, technology, engineering ...

123

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

124

News CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events  

NASA Astrophysics Data System (ADS)

CPD Event: Teaching day gives new perspectives Workshop: IOP network devolops its ideas Conference: Conference offers much to teachers Event: Physics is made easy in Liverpool Communication: IOSTE debates the complexities of STE Conference: Teaching event excites in Exeter Meeting Invitation: Wales physics meeting invites bookings CPD Event: Science teachers get hands on with development Research: Conference highlights liquid crytstal research in teaching Education: Teachers give positive feedback Science Fair: Science fair brings physics to students Teaching: Conference explores trends in teaching Forthcoming events

2010-09-01

125

Events | Physical Sciences in Oncology  

Cancer.gov

The 2015 AAAS Annual Meeting will include exciting work at the intersection of the physical and life sciences, including two sessions organized by NCI Physical Sciences-Oncology Network (PS-ON) Program Directors.

126

Behavioural Science for  

E-print Network

the core theory and methods of behavioural science and behavioural economics and how these can be applied and scientific activities of staff from Stirling's Behavioural Science Centre. This exciting course teaches to important business and policy relevant issues. Behavioural science and behavioural economics seek to answer

Little, Tony

127

Femtosecond Timescale Evolution of Pyrrole Electronic Excitation  

NASA Astrophysics Data System (ADS)

Pyrrole is a simple aromatic molecule with relevantchromophoric properties in biology. Although its apparent simplicity, it shows a complicated dynamics after excitation in the near part of the UV absorption spectrum, which results from the interplay between the bright ??^* and the dark dissociative ??^* electronic transitions. Herein, we present a time resolved study with ultrafast resolution on the relaxation dynamics of isolated pyrrole, after excitation in the 265-217 nm range. Two lifetimes of 19 and 15 fs, which are associated with the internal conversion from the bright 1B2 ??^* state and the propagation of the wavepacket on the ??^* state, respectively, are found in the studied energy interval. The work also explores the consequences of non resonant adiabatic excitation of the system when broadband femtosecond pulses are employed to prepare the molecule in the targeted electronic states, revealing the key implication of this type of coherent phenomena. The collected data reveal that the bright 1B2 ??^* state is adiabatically populated at excitation wavelengths far away from resonance, providing an efficient way to reach the ??^* state. The recorded transients are fit employing a coherent model that provides a comprehensive view of the dynamical processes pyrrole undergoes after excitation by ultrashort light pulses. M. N. R. Ashfold, B. Cronin, A. L. Devine, R. N. Dixon and M. G. D. Nix Science, 312, 1637-1640, 2006.

Montero, Raul; Conde, Alvaro Peralta; Ovejas, Virginia; Castano, Fernando; Longarte, Asier

2012-06-01

128

Excitation Methods for Bridge Structures  

SciTech Connect

This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

1999-02-08

129

Exciting flavored bound states  

NASA Astrophysics Data System (ADS)

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.

2014-10-01

130

Exciting flavored bound states  

E-print Network

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited $D_{(s)}$ mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.

E. Rojas; B. El-Bennich; J. P. B. C. de Melo

2014-10-23

131

Multi-photon excitation microscopy.  

PubMed

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

132

Multi-photon excitation microscopy  

PubMed Central

Multi-photon excitation (MPE) microscopy plays a growing role among microscopical techniques utilized for studying biological matter. In conjunction with confocal microscopy it can be considered the imaging workhorse of life science laboratories. Its roots can be found in a fundamental work written by Maria Goeppert Mayer more than 70 years ago. Nowadays, 2PE and MPE microscopes are expected to increase their impact in areas such biotechnology, neurobiology, embryology, tissue engineering, materials science where imaging can be coupled to the possibility of using the microscopes in an active way, too. As well, 2PE implementations in noninvasive optical bioscopy or laser-based treatments point out to the relevance in clinical applications. Here we report about some basic aspects related to the phenomenon, implications in three-dimensional imaging microscopy, practical aspects related to design and realization of MPE microscopes, and we only give a list of potential applications and variations on the theme in order to offer a starting point for advancing new applications and developments. PMID:16756664

Diaspro, Alberto; Bianchini, Paolo; Vicidomini, Giuseppe; Faretta, Mario; Ramoino, Paola; Usai, Cesare

2006-01-01

133

Positron excitation of neon  

NASA Technical Reports Server (NTRS)

The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

1990-01-01

134

The Astrophysics Science Division Annual Report 2008  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radio wavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. This report includes the Division's activities during 2008.

Oegerle, William; Reddy, Francis; Tyler, Pat

2009-01-01

135

Magnetostrictive resonance excitation  

DOEpatents

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

1992-01-01

136

Magnetic Excitations from Stripes in Cuprate Superconductors  

NASA Astrophysics Data System (ADS)

While it is generally believed that antiferromagnetic spin excitations play a significant role in the pairing mechanism of copper-oxide superconductors [1], the nature of the magnetic excitations themselves remains a matter of controversy. Recent measurements of the dispersion of spin excitations in superconducting YBa_2Cu_3O_6+x (YBCO) have attracted much attention. Here we present the results of comprehensive inelastic neutron scattering measurements of the momentum- and energy-dependent spectra of the magnetic fluctuations in La_0.875Ba_0.125CuO_4, which exhibits inhomogeneous, charge-stripe order. We will also point out universalities and differences in the magnetic excitation spectra compared to related charge-stripe ordered compounds and high-temperature superconductors, including La_2-xSr_xNiO4 and YBCO. JMT, HW, GDG and GX are supported by U.S. Department of Energy contract # DE-AC02-98CH1088 [1] J. Orenstein and A. J. Millis, Science 288, 468 (2000).

Tranquada, J. M.; Woo, H.; Perring, T. G.; Goka, H.; Gu, G. D.; Xu, G.; Fujita, M.; Yamada, K.

2004-03-01

137

Apparatus for photon excited catalysis  

NASA Technical Reports Server (NTRS)

An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

Saffren, M. M. (inventor)

1977-01-01

138

Harmonically excited orbital variations  

SciTech Connect

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

Morgan, T.

1985-08-06

139

Aperture excited dielectric antennas  

NASA Technical Reports Server (NTRS)

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

1974-01-01

140

Capturing Excitement: Oceanography  

ERIC Educational Resources Information Center

Describes four elementary school earth science activities. Each student experience is designed to help children answer questions about the ocean floor, continental drift, volcanism and mountain chains. Includes a bibliography of related articles, books, and maps. (JM)

Boyer, Robert E.; Butts, David P.

1971-01-01

141

Seasonal excitation of polar motion  

NASA Astrophysics Data System (ADS)

We estimate geophysical excitations (?1 and ?2) of polar motion using multiple sources of data, including recent atmospheric, oceanic, and hydrological models, satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE), and compare geophysical excitations with observed polar motion excitations from space geodetic techniques. At seasonal time scales, both model-estimated excitations from the geophysical fluids envelope (i.e., atmosphere, ocean, and hydrosphere) and GRACE-observed excitations agree remarkably well with polar motion observations in the ?2 component, and in the ?1 component, model estimates and observed geodetic excitations show significant discrepancies. However, mass excitations estimated from GRACE show significantly better agreement with observed excitations than those from models, especially in ?1, due to better quantification of terrestrial water storage and oceanic mass changes using GRACE data. Furthermore, GRACE satellite gravity measurements offer a unique means for quantifying contributions from cryospheric angular momentum (CAM) change, a component mostly neglected in previous studies due to the lack of adequate observations or reliable ice sheets models. Based on GRACE estimates, CAM excitations appear a minor, but not negligible contributor to seasonal excitations of polar motion. The significantly better agreement in ?2 (than that in ?1) between observations and model excitations is related to the higher sensitivity of ?2 excitations to atmospheric pressure and terrestrial water changes over the Eurasia and North American continents, because of the special relationship between the ?S21 spherical harmonic coefficient (proportional to ?2) mass model and the locations of the two continents.

Chen, J. L.; Wilson, C. R.; Zhou, Y. H.

2012-12-01

142

Get excited: reappraising pre-performance anxiety as excitement.  

PubMed

Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. PMID:24364682

Brooks, Alison Wood

2014-06-01

143

Analysis and Interpretation of Hard X-ray Emission fromthe Bullet Cluster (1E0657-56), the Most Distant Cluster of Galaxies Observed by the RXTE  

SciTech Connect

Evidence for non-thermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the Extreme Ultraviolet and Hard X-ray ranges have provided for more powerful tools for the investigation of this phenomenon. Detection of hard X-rays in the 20 to 100 keV range have been reported from several clusters of galaxies, notably from Coma and others. Based on these earlier observations we identified the relatively high redshift cluster 1E0657-56 (also known as RX J0658-5557) as a good candidate for hard X-ray observations. This cluster, also known as the bullet cluster, has many other interesting and unusual features, most notably that it is undergoing a merger, clearly visible in the X-ray images. Here we present results from a successful RXTE observations of this cluster. We summarize past observations and their theoretical interpretation which guided us in the selection process. We describe the new observations and present the constraints we can set on the flux and spectrum of the hard X-rays. Finally we discuss the constraints one can set on the characteristics of accelerated electrons which produce the hard X-rays and the radio radiation.

Petrosian, Vahe; /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept.; Madejski, Greg; /SLAC; Luli, Kevin; /Stanford U., Phys. Dept.

2006-08-16

144

10 Years of RXTE Monitoring of the Anomalous X-Ray Pulsar 4U 0142+61: Long-Term Variability  

NASA Astrophysics Data System (ADS)

We report on 10 years of monitoring of the 8.7 s anomalous X-ray pulsar 4U 0142+61 using the Rossi X-Ray Timing Explorer (RXTE). This pulsar exhibited stable rotation from 2000 March until 2006 February; the rms phase residual for a spin-down model, which includes ?, ??, and ??, is 2.3%. We report a possible phase-coherent timing solution valid over a 10 yr span extending back to 1996 March. A glitch may have occurred between 1998 and 2000, but is not required by the existing timing data. The pulse profile has been evolving since 2000. In particular, the dip of emission between its two peaks got shallower between 2002 and 2006, as if the profile were evolving back to its pre-2000 morphology, following an earlier event, which possibly also included the glitch suggested by the timing data. These profile variations are seen in the 2-4 keV band, but not in 6-8 keV. We also detect a slow increase in the pulsed flux between 2002 May and 2004 December, such that it has risen by 36%+/-3% over 2.6 yr in the 2-10 keV band. The pulsed flux variability and the narrowband pulse profile changes present interesting challenges to aspects of the magnetar model.

Dib, Rim; Kaspi, Victoria M.; Gavriil, Fotis P.

2007-09-01

145

Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State  

SciTech Connect

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; /Heidelberg, Max Planck Inst. /Dublin Inst.; Akhperjanian, A.G.; /Yerevan Phys. Inst.; Anton, G.; /Erlangen - Nuremberg U.; Barres de Almeida, U.; /Durham U.; Bazer-Bachi, A.R.; /Toulouse, CESR; Becherini, Y.; /APC, Paris; Behera, B.; /Heidelberg Observ.; Bernlohr, K.; /Heidelberg, Max Planck Inst. /Humboldt U., Berlin; Boisson, C.; /LUTH, Meudon; Bochow, A.; /Heidelberg, Max Planck Inst.; Borrel, V.; /Toulouse, CESR; Brion, E.; /DAPNIA, Saclay; Brucker, J.; /Erlangen - Nuremberg U.; Brun, P.; /DAPNIA, Saclay; Buhler, R.; /Heidelberg, Max Planck Inst.; Bulik, T.; /Warsaw, Copernicus Astron. Ctr.; Busching, I.; /Western Ontario U.; Boutelier, T.; /Grenoble Observ.; Chadwick, P.M.; /Durham U.; Charbonnier, A.; /Paris U., VI-VII; Chaves, R.C.G.; /Heidelberg, Max Planck Inst. /Durham U. /Ecole Polytechnique /Heidelberg, Max Planck Inst. /Annecy, LAPP /Humboldt U., Berlin /Durham U. /Namibia U. /Western Ontario U. /Ecole Polytechnique /Heidelberg, Max Planck Inst. /Durham U. /APC, Paris /Heidelberg, Max Planck Inst. /Dublin Inst. /Annecy, LAPP /Grenoble Observ. /Warsaw, Copernicus Astron. Ctr. /Cracow, INP /Heidelberg, Max Planck Inst. /Heidelberg Observ. /APC, Paris /Montpellier U. /Montpellier U. /Montpellier U. /Heidelberg, Max Planck Inst. /Ecole Polytechnique /Humboldt U., Berlin /Dublin Inst. /Montpellier U. /APC, Paris /SLAC; /more authors..

2009-05-07

146

SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE  

SciTech Connect

We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

Aharonian, F.; Bernloehr, K.; Bochow, A.; Buehler, R. [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, D-69029 Heidelberg (Germany); Akhperjanian, A. G. [Yerevan Physics Institute, 2 Alikhanian Brothers Street, 375036 Yerevan (Armenia); Anton, G.; Brucker, J. [Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany); Barres de Almeida, U.; Chadwick, P. M. [University of Durham, Department of Physics, South Road, Durham DH1 3LE (United Kingdom); Bazer-Bachi, A. R.; Borrel, V. [Centre d'Etude Spatiale des Rayonnements, CNRS/UPS, BP 44346, F-31028 Toulouse Cedex 4 (France); Becherini, Y. [Astroparticule et Cosmologie (APC), CNRS, Universite Paris 7 Denis Diderot, 10, rue Alice Domon et Leonie Duquet, F-75205 Paris Cedex 13 (France); Behera, B. [Landessternwarte, Universitaet Heidelberg, Koenigstuhl, D-69117 Heidelberg (Germany); Boisson, C. [LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, 5 Place Jules Janssen, 92190 Meudon (France); Brion, E.; Brun, P. [IRFU/DSM/CEA, CE Saclay, F-91191 Gif-sur-Yvette, Cedex (France); Bulik, T. [Nicolaus Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warsaw (Poland); Buesching, I. [Unit for Space Physics, Northwest University, Potchefstroom 2520 (South Africa); Boutelier, T. [Laboratoire d'Astrophysique de Grenoble, INSU/CNRS, Universite Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9 (France); Charbonnier, A. [LPNHE, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS/IN2P3, 4 Place Jussieu, F-75252, Paris Cedex 5 (France)], E-mail: lucie.gerard@apc.univ-paris7.fr, E-mail: berrie@in2p3.fr, E-mail: sanchez@poly.in2p3.fr, E-mail: jchiang@slac.stanford.edu (and others)

2009-05-10

147

The Fall and the Rise of X-Rays from Dwarf Novae in Outburst: RXTE Observations of VW Hydri and WW Ceti  

NASA Technical Reports Server (NTRS)

In a dwarf nova, the accretion disk around the white dwarf is a source of ultraviolet, optical, and infrared photons, but is never hot enough to emit X-rays. Observed X-rays instead originate from the boundary layer between the disk and the white dwarf. As the disk switches between quiescence and outburst states, the 2-10 keV X-ray flux is usually seen to be anti-correlated with the optical brightness. Here we present RXTE monitoring observations of two dwarf novae, VW Hyi and WW Cet, confirming the optical/X-ray anti-correlation in these two systems. However, we do not detect any episodes of increased hard X-ray flux on the rise (out of two possible chances for WW Cet) or the decline (two for WW Cet and one for VW Hyi) from outburst, attributes that are clearly established in SS Cyg. The addition of these data to the existing literature establishes the fact that the behavior of SS Cyg is the exception, rather than the archetype as is often assumed. We speculate that only dwarf novae with a massive white dwarf may show these hard X-ray spikes.

Fertig, D.; Mukai, K.; Nelson, T.; Cannizzo, J. K.

2011-01-01

148

Extreme Science  

NSDL National Science Digital Library

Have you ever wondered how tides are created, where the greatest earthquake happened, or how time is measured? All of these and many more questions are answered at this fantastic website created by scientist, Elizabeth Keller. Users can find an abundance of materials on time, weather, space phenomena, and earth science. Within the Gallery of Scientists, users can learn about the work of admirable researchers. Packed with fun statistics and amazing images, this website will help educators get students excited about learning.

Keller, Elizabeth

149

Why pursue the Master of Science in Chemistry?  

E-print Network

Why pursue the Master of Science in Chemistry? College of Natural Sciences and Mathematics Because of its broad scope, contemporary chemistry offers exciting em- ployment opportunities in rapidly growing fields, such as materials science, polymers, biochemistry, biotechnology, pharmaceutical

de Lijser, Peter

150

Science Career Magazine.  

ERIC Educational Resources Information Center

This magazine is designed for teachers and students in junior and senior high schools. It is intended to help students become more aware about what scientists and engineers do, what's new and exciting in the fields of science and engineering, and what satisfactions might be expected from a career in one of the many different areas of science and

Halsey, Linda B., Ed.; Sweeley, Charles C., Ed.

151

Self-excitation of single nanomechanical pillars  

NASA Astrophysics Data System (ADS)

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005 J. Sol. Energy Eng. 127 581-7). In other words, a static force, such as the wind acting on rotor blades, can generate a resonant excitation at a certain mechanical frequency. For nanomechanical systems (Craighead 2000 Science 290 1532-5 Roukes 2001 Phys. World 14 25-31 Cleland 2003 Foundations of Nanomechanics (Berlin: Springer); Ayari et al 2007 Nano Lett. 7 2252-7 Koenig et al 2008 Nat. Nanotechnol. 3 482-4) such a self-excitation (SE) mechanism is also highly desirable, because it can generate mechanical oscillations at radio frequencies by simply applying a dc bias voltage. This is of great importance for low-power signal communication devices and detectors, as well as for mechanical computing elements. For a particular nanomechanical systemthe single electron shuttlethis effect was predicted some time ago by Gorelik et al (Phys. Rev. Lett. 80 4526-9). Here, we use a nanoelectromechanical single electron transistor (NEMSET) to demonstrate self-excitation for both the soft and hard regimes, respectively. The ability to use self-excitation in nanomechanical systems may enable the detection of quantum mechanical backaction effects (Naik et al 2006 Nature 443 193-6) in direct tunneling, macroscopic quantum tunneling (Savelev et al 2006 New J. Phys. 8 105-15) and rectification (Pistolesi and Fazio 2005 Phys. Rev. Lett. 94 036806-4). All these effects have so far been overshadowed by the large driving voltages that had to be applied.

Kim, Hyun S.; Qin, Hua; Blick, Robert H.

2010-03-01

152

Excited States and Photons  

NSDL National Science Digital Library

Investigate how atoms can be excited to give off radiation (photons) with models of electron energy diagrams. Explore the effects of energy levels in atoms through interactive computer models. Learn about the different electron orbitals of an atom, and explore three-dimensional models of the atoms. Learn about photons and why they are emitted, and gain an understanding of the link between energy levels and photons as you discover how an atom?s electron configuration affects which wavelengths of light it will admit or absorb.

The Concord Consortium

2011-12-13

153

Dipole Excitation of Dipositronium  

E-print Network

The energy interval between the ground and the P-wave excited states of the recently discovered positronium molecule Ps_2 is evaluated, including the relativistic and the leading logarithmic radiative corrections, E_P-E_S = 0.181 586 7(8) a.u. The P-state, decaying usually via annihilation, is found to decay into the ground state by an electric dipole transition 19 percent of the time. Anticipated observation of this transition will provide insight into this exotic system.

Mariusz Puchalski; Andrzej Czarnecki

2008-09-30

154

Learn some exciting, simple, low-cost experiments to engage your students!  

E-print Network

using everyday materials that can be integrated into your existing lesson plans. Why: To engage: High school general science, chemistry, physics, math and technology teachers; middle school science and excite young people in science and math! Where & When: Northern Illinois University DeKalb Campus

Kostic, Milivoje M.

155

National Computational Science Education Consortium (NCSEC)  

NSDL National Science Digital Library

Serving as a national educational computational science clearinghouse, this website offers math and science teachers everywhere an array of online educational tools and exciting teaching modules that can be used in the classroom.

156

Who Am I? ASE Science Year Resources: Bringing Science Year into the Classroom. [CD-ROM].  

ERIC Educational Resources Information Center

This CD-ROM describes how science can be used in schools to show that students can be excited and engaged in science and how science can be integrated into other disciplines. Science Year is a 12-month packed calendar of events, projects and resources, designed to stimulate the imagination about science and technology. Activities include the

Association for Science Education, Herts (England).

157

Neutron Scattering Studies of spin excitations in hole-doped  

E-print Network

Neutron Scattering Studies of spin excitations in hole-doped Ba0.67K0.33Fe2As2 superconductor Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA, 4 University, West Lafayette, Indiana 47907, USA. We report inelastic neutron scattering experiments on single

Wang, Wei Hua

158

Density Functional Theory for Excited States  

NASA Astrophysics Data System (ADS)

Using the concept of entangled states it is shown that density functional theory in its initial ground-state formulationfootnotetextP. Hohenberg and W. Kohn, Phys. Rev. 136, B864, (1964).^,footnotetextW. Kohn and L. J. Sham, Phys. Rev. 140, A1133 (1965).^,footnotetextM. Levy, Proc. Nat. Acad. Sci. USA 76, 6062 (1979). is inherently capable of treating the excited states of interacting many-particle systems.footnotetextAcknowledgement: Discussions with Mel Levy are gratefully acknowledged. This work was performed under the auspices of the U.S. Department of Energy under Contract DE-AC52-07NA27344 with LLNS, LLC. Work at ORNL was performed under the auspices of the Division of Materials Science and Engineering and at CNMS by the Division of Scientific User Facilities, Office of Basic Energy Science of the US Department of Energy.

Gonis, Antonios; Nicholson, Don M.; Zhang, X.-G.; Stocks, G. Malcolm; Chiesa, Simone

2010-03-01

159

Science Sampler: Growth Potential  

NSDL National Science Digital Library

Students will enjoy carrying out this exciting and challenging research project that combines science with computers and mathematics to investigate how polyacrylate animals change in size over time when placed in water and aqueous salt solutions. The hands-on activity motivates students and provides them with enjoyable and rewarding science project experiences. Here they have an opportunity to solve a problem and use the science inquiry skills of observing, collecting, organizing, and analyzing data.

Dana M. Barry

2004-04-01

160

Axonal excitability revisited.  

PubMed

The original papers of Hodgkin and Huxley (J. Physiol. 116 (1952a) 449, J. Physiol. 116 (1952b) 473, J. Physiol. 116 (1952c) 497, J. Physiol. 117 (1952d) 500) have provided a benchmark in our understanding of cellular excitability. Not surprisingly, their model of the membrane action potential (AP) requires revisions even for the squid giant axon, the preparation for which it was originally formulated. The mechanisms they proposed for the voltage-gated potassium and sodium ion currents, IK, and INa, respectively, have been superceded by more recent formulations that more accurately describe voltage-clamp measurements of these components. Moreover, the current-voltage relation for IK has a non-linear dependence upon driving force that is well described by the Goldman-Hodgkin-Katz (GHK) relation, rather than the linear dependence on driving force found by Hodgkin and Huxley. Furthermore, accumulation of potassium ions in the extracellular space adjacent to the axolemma appears to be significant even during a single AP. This paper describes the influence of these various modifications in their model on the mathematically reconstructed AP. The GHK and K+ accumulation results alter the shape of the AP, whereas the modifications in IK and INa gating have surprisingly little effect. Perhaps the most significant change in their model concerns the amplitude of INa, which they appear to have overestimated by a factor of two. This modification together with the GHK and the K+ accumulation results largely remove the discrepancies between membrane excitability of the squid giant axon and the Hodgkin and Huxley (J. Physiol. 117 (1952d) 500) model previously described (Clay, J. Neurophysiol. 80 (1998) 903). PMID:15561301

Clay, John R

2005-05-01

161

Multiphoton excitation of fluorescent probes.  

PubMed

This introduction reviews the multiphoton excitation cross sections of extrinsic and intrinsic fluorophores, genetically engineered probes, and nanoparticles. We will review the known two-photon excitation cross sections of biological indicators and will discuss several related issues such as how to theoretically estimate and experimentally gauge the two-photon cross section of an indicator. We provide practical guides for experimentally estimating the excitation cross section. PMID:25734074

Xu, Chris; Zipfel, Warren R

2015-01-01

162

Optically excited states in positronium  

NASA Technical Reports Server (NTRS)

Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

1990-01-01

163

Plasmon excitation by slow ions  

NASA Astrophysics Data System (ADS)

We present a theoretical approach to the problem of subthreshold plasmon excitation in proton-aluminum collisions. Based both on recent experimental results by Ritzau [Phys. Rev. B 59, 15506 (1999)] and on previous calculations by two of the authors, we solve the master equations and obtain the probability of both plasmon excitation and nearly free electron excitation due to plasmon decay as functions of the projectile initial velocity. The mechanism considered for subthreshold plasmon excitation involves an intermediary fast electron as suggested by Ritzau

Bocan, G. A.; Arista, N. R.; Miraglia, J. E.

2007-01-01

164

RXTE Monitoring of the Anomalous X-ray Pulsar 1E 1048.1-5937: Long-Term Variability and the 2007 March Event  

NASA Technical Reports Server (NTRS)

After three years of no unusual activity, Anomalous X-ray Pulsar 1E 1048.1-5937 reactivated in 2007 March. We report on the detection of a large glitch (deltav/v = 1.63(2) x 10(exp -5)) on 2007 March 26 (MJD 54185.9), contemporaneous with the onset of a pulsed-flux flare, the third flare observed from this source in 10 years of monitoring with the Rossi X-ray Timing Explorer. Additionally, we report on a detailed study of the evolution of the timing properties, the pulsed flux, and the pulse profile of this source as measured by RXTE from 1996 July to 2008 January. In our timing study, we attempted phase coherent timing of all available observations. We show that in 2001, a timing anomaly of uncertain nature occurred near the rise of the first pulsed flux flare; we show that a likely glitch (deltav/v = 2.91(9) x 10(exp -6)) occurred in 2002, near the rise of the second flare, and we present a detailed description of the variations in the spin-down. In our pulsed flux study, we compare the decays of the three flares and discuss changes in the hardness ratio. In our pulse profile study, we show that the profile exhibited large variations near the peak of the first two flares, and several small short-term profile variations during the most recent flare. Finally, we report on the discovery of a small burst 27 days after the peak of the last flare, the fourth burst discovered from this source. We discuss the relationships between the observed properties in the framework of the magnetar model.

Dib, Rim; Kaspi, Victoria M.; Gavriil, Fotis P.

2009-01-01

165

'pseudo' Phase resolved spectroscopy of "Hear-beat" oscillations in IGR J17091-3624 with simultaneous XMM-Newton and RXTE observations  

NASA Astrophysics Data System (ADS)

IGR J17091-3624 is an X-ray transient discovered by INTEGRAL in April 2003 and is believed to be a galactic black hole candidate. It came into prominence during its recent outburst in February 2011 due to peculiar 'heart-beat' type variability patterns exhibited by the source in which the quasi-periodic mini-outbursts are repeated over time scale as short as 5 seconds. So far such variability pattern is observed only in GRS1915+105, which is famous for displaying variety of short term variability patterns. However, GRS1915+105 is considered to be an isolated exhibiting extreme variability whereas all other sources exhibit much gentler variability and over much longer time scale. Thus observation of 'heart-beat' type of short term variability in IGR J17091-3624 promotes it as missing-link between GRS1915+105 and rest of black-hole binaries. However, the possibility of in-depth study of the origin of such variability is hampered by complete lack of knowledge about the distance, black hole mass as well as inclination angle. Here we present the results of 'pseudo' phase resolved spectroscopy of simultaneous XMM-Newton and RXTE observations, which can constrain at least some of the unknown geometric parameters. This work demonstrates the importance of wide band X-ray spectroscopy of by simultaneous observations with focusing X-ray telescope and large area collimated detectors. Normally such simultaneous observations with different observatories are very difficult to realize due to variety of constraints, but with Astrosat these will be available by default and hence Astrosat will be ideally suitable for wide band X-ray spectroscopy of Galactic X-ray sources.

Vadawale, Santosh; Rao, Anjali

2012-07-01

166

RXTE Observations of Anomalous X-ray Pulsar 1E 1547.0-5408 During and After its 2008 and 2009 Outbursts  

NASA Technical Reports Server (NTRS)

We present the results of Rossi X-ray Timing Explorer (RXTE) and Swift monitoring observations of the magnetar 1E 1547.0-5408 following the pulsar's radiative outbursts in 2008 October and 2009 January. We report on a study of the evolution of the timing properties and the pulsed flux from 2008 October 4 through 2009 December 26. In our timing study, a phase-coherent analysis shows that for the first 29 days following the 2008 outburst, there was a very fast increase in the magnitude of the rotational frequency derivative upsilon-dot, such that upsilon-dot-dot was a factor of 60 larger than that reported in data from 2007. This upsilon-dot magnitude increase occurred in concert with the decay of the pulsed flux following the start of the 2008 event. Following the 2009 outburst, for the first 23 days, upsilon-dot-dot was consistent with zero, and upsilon-dot had returned to close to its 2007 value. In contrast to the 2008 event, the 2009 outburst showed a major increase in persistent flux, relatively little change in the pulsed flux, and sudden significant spectral hardening approx 15 days after the outburst. We show that, excluding the month following each of the outbursts, and because of the noise and the sparsity in the data, multiple plausible timing solutions fit the pulsar's frequency behavior. We note similarities in the behavior of 1E 1547.0-5408 following the 2008 outburst to that seen in the AXP 1E 1048.1-5937 following its 2001-2002 outburst and discuss this in terms of the magnetar model.

Dib, Rim; Kaspi, Victoria M.; Scholz, Paul; Gavriil, Fotis P.

2012-01-01

167

Long-term Multi-wavelength Studies of GRS 1915+105. I. A High-energy and Mid-infrared Focus with RXTE/INTEGRAL and Spitzer  

NASA Astrophysics Data System (ADS)

To date, mid-infrared properties of Galactic black hole binaries have barely been investigated in the framework of multi-wavelength campaigns. Yet, studies in this spectral domain are crucial to get complementary information on the presence of dust and/or on the physical processes such as dust heating and thermal bremsstrahlung. Here, we report a long-term multi-wavelength study of the microquasar GRS 1915+105. On the one hand, we aimed at understanding the origins of the mid-infrared emission, and on the other hand, at searching for correlation with the high-energy and/or radio activities. We observed the source at several epochs between 2004 and 2006 with the photometer IRAC and spectrometer IRS, both mounted on the Spitzer Space Telescope. When available, we completed our set of data with quasi-simultaneous RXTE/INTEGRAL high-energy and/or Ryle radio observations from public archives. We then studied the mid-infrared environment and activities of GRS 1915+105 through spectral analysis and broadband fitting of its radio to X-ray spectral energy distributions. We detected polycyclic aromatic hydrocarbon molecules in all but one IRS spectra of GRS 1915+105 which unambiguously proves the presence of a dust component, likely photoionized by the high-energy emission. We also argue that this dust is distributed in a disk-like structure heated by the companion star, as observed in some Herbig Ae/Be and isolated cool giant stars. Moreover, we show that some of the soft X-ray emission emanating from the inner regions of the accretion disk is reprocessed and thermalized in the outer part. This leads to a mid-infrared excess that is very likely correlated to the soft X-ray emission. We exclude thermal bremsstrahlung as contributing significantly in this spectral domain.

Rahoui, F.; Chaty, S.; Rodriguez, J.; Fuchs, Y.; Mirabel, I. F.; Pooley, G. G.

2010-06-01

168

Follow-Up with Students after 6 Years of Participation in Project Excite  

ERIC Educational Resources Information Center

Project EXCITE is a program for minority students that supplements the regular school offerings with an emphasis on enhancing students' interest and performance in math and science. This study examines the experience and perceptions of 14 student participants in the program and their parents. In student and parent interviews, Project EXCITE was

Lee, Seon-Young; Olszewski-Kubilius, Paula; Peternel, George

2009-01-01

169

The Balloons Go Up for Science.  

ERIC Educational Resources Information Center

Describes the planning and implementation of a science week intended to raise the awareness of science in an elementary school. Educational requirements included exciting science happenings and concentrated science teaching of a high standard. The week included demonstrations, guest speakers, and schoolwide assemblies. Demonstrations included the

Fayle, Maureen

1998-01-01

170

Super Science Saturday  

NSDL National Science Digital Library

Looking for a way to excite teachers and families about your school's science program? A "Super Science Saturday" can provide a safe, fun, and interactive educational experience to do just that. When a community collaborates to plan and implement exciting science activities for area families, you can create a buzz about science at your school.A successfully established collaboration between the University of St. Thomas, a small liberal arts Catholic university in Houston, Texas, and a local elementary school, Helms Community Learning Center was the perfect model for involving families and the community. In just two years, this science event has become a much-anticipated family outing that draws current students, younger siblings, and even former students to attend.

Rick Krustchinsky

2003-01-01

171

The Excitable Membrane  

PubMed Central

The model of the excitable membrane assumes common channels for Na+ and K+; the two ion species interact within the pores through their electrostatic forces. The electric field varies across the membrane and with time, as a result of ionic redistribution. Ionic flow is primarily controlled by energy barriers at the two interfaces and by Ca++ adsorption at the external interface. When the membrane is polarized, the high electric field at the external interface acting on the membrane fixed charge keeps the effective channel diameter small, so that only dihydrated ions can cross the interface. The higher energy required to partially dehydrate Na+ accounts for its lower permeability when polarized. Depolarized, the channel entrance can expand, permitting quadrihydrated ions to pass; the large initial Na+ flow is the result of the large concentration ratio across the interface. The effect at the internal interface is symmetric; Na+ crosses with greater difficulty when the membrane is depolarized. Na+ inactivation occurs when the ion distribution within the membrane has assumed its new steady-state value. Calculations based on parameters consistent with physicochemical data agree generally with a wide range of experiments. The model does not obey the two fundamental Hodgkin-Huxley (HH) postulates (independence principle, ion flow proportional to thermodynamic potential). In several instances the model predicts experimental results which are not predicted by the HH equations. ImagesFIGURE 12 PMID:4655662

Offner, Franklin F.

1972-01-01

172

Excited waves in shear layers  

NASA Technical Reports Server (NTRS)

The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

Bechert, D. W.

1982-01-01

173

Vibrational excitation induces double reaction.  

PubMed

Electron-induced reaction at metal surfaces is currently the subject of extensive study. Here, we broaden the range of experimentation to a comparison of vibrational excitation with electronic excitation, for reaction of the same molecule at the same clean metal surface. In a previous study of electron-induced reaction by scanning tunneling microscopy (STM), we examined the dynamics of the concurrent breaking of the two C-I bonds of ortho-diiodobenzene physisorbed on Cu(110). The energy of the incident electron was near the electronic excitation threshold of E0=1.0 eV required to induce this single-electron process. STM has been employed in the present work to study the reaction dynamics at the substantially lower incident electron energies of 0.3 eV, well below the electronic excitation threshold. The observed increase in reaction rate with current was found to be fourth-order, indicative of multistep reagent vibrational excitation, in contrast to the first-order rate dependence found earlier for electronic excitation. The change in mode of excitation was accompanied by altered reaction dynamics, evidenced by a different pattern of binding of the chemisorbed products to the copper surface. We have modeled these altered reaction dynamics by exciting normal modes of vibration that distort the C-I bonds of the physisorbed reagent. Using the same ab initio ground potential-energy surface as in the prior work on electronic excitation, but with only vibrational excitation of the physisorbed reagent in the asymmetric stretch mode of C-I bonds, we obtained the observed alteration in reaction dynamics. PMID:25489788

Huang, Kai; Leung, Lydie; Lim, Tingbin; Ning, Zhanyu; Polanyi, John C

2014-12-23

174

Radioactivity Induced by Nuclear Excitation I. Excitation by Neutrons  

Microsoft Academic Search

It is shown that the 4.1-hr. period of indium can be produced by nuclear excitation of indium and is to be attributed to an excited metastable state, In115,* of the stable In115. This result is obtained by studying the radioactivity produced in indium by neutrons of different energy distributions and by studying the chain reactions produced in cadmium by fast

M. Goldhaber; R. D. Hill; Leo Szilard

1939-01-01

175

Uniform excitations in magnetic nanoparticles.  

PubMed

We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T(3/2) law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mssbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Mrup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

176

Uniform excitations in magnetic nanoparticles  

PubMed Central

Summary We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T 3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mssbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering. PMID:21977393

Frandsen, Cathrine; Hansen, Mikkel Fougt

2010-01-01

177

Coulomb excitation of 107In  

NASA Astrophysics Data System (ADS)

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two ? rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2- states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code gosia2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekstrm, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhuser, R.; Grgen, A.; Hess, H.; Heyde, K.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2013-01-01

178

Effects of dark atom excitations  

E-print Network

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Jean-Ren Cudell; Maxim Yu. Khlopov; Quentin Wallemacq

2014-11-06

179

YES Mag: Science Projects  

NSDL National Science Digital Library

Parents, are you looking for a way to excite your children about science? This website developed by YES Mag, Canada's science magazine for kids, may just have the answer. Users can find numerous fun science activities addressing many of the basic science principles and phenomena including Newton's third law, lightening, wind, and chromatography. Each activity includes pictures to assist in the implementation of the project as well as a convenient printable version. With over thirty-five activities, children are sure to have a fun learning experience.

180

A Comparison of the Variability of the Symbiotic X-ray Binaries GX 1+4, 4U 1954+31, and 4U 1700+24 from Swift/BAT and RXTE/ASM Observations  

NASA Technical Reports Server (NTRS)

We present an analysis of the X-ray variability of three symbiotic X-ray binaries, GX 1+4, 4U 1700+24, and 4U 1954+31, using observations made with the Swift Burst Alert Telescope (BAT) and the Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor (ASM). Observations of 4U 1954+31 with the Swift BAT show modulation at a period near 5 hours. Models to explain this modulation are discussed including the presence of an exceptionally slow X-ray pulsar in the system and accretion instabilities. We conclude that the most likely interpretation is that 4U 1954+31 contains one of the slowest known X-ray pulsars. Unlike 4U 1954+31, neither GX 1+4 nor 4U 1700+24 show any evidence for modulation on a timescale of hours. An analysis of the RXTE ASM light curves of GX l+4, 4U 1700+24, and 4U 1954+31 does not show the presence of periodic modulation in any source, although there is considerable variability on long timescales for all three sources. There is no modulation in GX 1+4 on either the optical 1161 day orbital period or a previously reported 304 day X-ray period. For 4U 1700+24 we do not confirm the 404 day period previously proposed for this source from a shorter duration ASM light curve.

Corbet, R. H. D.; Sokoloski, J. L.; Mukai, K.; Markwardt, C. B.; Tueller, J.

2007-01-01

181

Industrial applications of photonuclear resonance excitation  

E-print Network

Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

Chichester, David Lee, 1971-

2000-01-01

182

Laser-induced nuclear excitation  

SciTech Connect

An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 10{sup 3} Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

Zon, B. A., E-mail: zon@niif.vsu.ru; Kornev, A. S., E-mail: a-kornev@yandex.r [Voronezh State University (Russian Federation)

2010-05-15

183

Redox Control of Cardiac Excitability  

PubMed Central

Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432468. PMID:22897788

Aggarwal, Nitin T.

2013-01-01

184

Electron-excited molecule interactions  

SciTech Connect

In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

Christophorou, L.G. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1991-01-01

185

Mission Statement The College of Sciences and Mathematics at Auburn University aims to promote  

E-print Network

-12 students to reach their full potential in science by providing them with access to exciting, hands students to share their passion for science with a broad audience · To provide professional development4 Mission Statement The College of Sciences

Tam, Tin-Yau

186

Faculty of Science Medical Physics  

E-print Network

Faculty of Science Medical Physics If you like physics and mathematics, but want a career in the rapidly expanding health sciences, then this honours BSc is for you. www.uwindsor.ca/physics Medical in Medical Physics lays the foundation for an exciting and rewarding career in Medical Physics. Rigorous

187

Wave excited cable mooring dynamics by modal analysis  

E-print Network

mooring cables are wrdely used to restrain surface structures such as buoys, drilling platforms, ships, and subsurface equipr, . ent such as oceano- graphic arrays. Typical moorings consist of one or more flexible cables which have one end fixed...klAVE EXCITED CABLE MOORING DYNAMICS BY MODAL ANALYSIS A Thesis RICHARD EARL DAVIS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1977 Major...

Davis, Richard Earl

1977-01-01

188

Science Shorts: More Than One Way to Investigate  

NSDL National Science Digital Library

An exciting element of science fairs is that they give students the opportunity to explore various interests through scientific investigation. Many students, however, mistakenly think that all investigations are experiments. This lesson can help broaden students' conceptions of science.

2007-12-01

189

The syndrome of excited delirium.  

PubMed

The excited delirium syndrome (EDS) is a life-threatening condition caused by a variety of factors including drug intoxication and psychiatric illness. Fatal instances of excited delirium frequently come to the attention of the medical examiner/coroner due to the circumstances and potential causes. Excited delirium may include paranoid, aggressive, and incoherent behavior which may lead to an encounter with law enforcement. In some instances, the person may die while in the presence of law enforcement. This circumstance further broadens the potential causes of death particularly as EDS has no pathognomonic autopsy finding. Although the syndrome of excited delirium is sufficient to explain death, other intervening causes need to be considered. These include chest or neck compression during restraint, blunt trauma, and underlying natural disease. Since chest/neck compression, natural disease (e.g., atherosclerosis), blunt trauma, and excited delirium are not mutually exclusive, all may be present in one death. The forensic pathologist's role is to determine what caused and/or contributed to the death. When attempting to determine the proximate cause of death in instances with multiple potential causes, determining the mechanism of death often is useful. As not all causes of death have pathologically-demonstrable mechanisms of death, examination of the circumstances of the death often are diagnostically important. The main goal of the autopsy of deaths suspected to be due to EDS is to identify (or exclude) intervening diseases or injuries sufficient to explain the death in the context of the investigated circumstances. PMID:24526411

Gill, James R

2014-06-01

190

No Compton Reflection In a Chandra/RXTE Observation of Mkn 509: Implications for the Fe-K Line Emission From Accreting X-Ray Sources  

NASA Technical Reports Server (NTRS)

We report the results of simultaneous Chandra and RXTE observations of the Seyfert 1 galaxy Mkn 509. We deconvolve the broad and narrow Fe-K emission-line components for which we measure rest-frame equivalent widths of 119+/-18 eV and 57+/-13 eV respectively. The broad line has a FWHM of 57,600((sup 14,400)(sub -21,000)) km/s and the narrow line is unresolved, with an upper limit on the FWHM of 4,940 km/s. Both components must originate in cool matter since we measure rest-frame center energies of 6.36((sup +0.13)(sub -0.12)) keV and 6.42+/-0.01 keV for the broad and narrow line respectively. This rules out He-like and H-like Fe for the origin of both the broad and narrow lines. If, as is widely accepted, the broad Fe-K line originates in Thomson-thick matter (such as an accretion disk), then one expects to observe spectral curvature above approximately 10 keV, (commensurate with the observed broad line), characteristic of the Compton-reflection continuum. However our data sets very stringent limits on deviations of the observed continuum from a power law. Light travel-time delays cannot be invoked to explain anomalies in the relative strengths of the broad Ferry line and Compton-reflection continuum since they are supposed to originate in the same physical location. We are forced to conclude that both the broad and narrow Fe-K lines had to originate in Thomson-thin matter during our observation. This result, for a single observation of just one source, means that our understanding of Fe K line emission and Compton reflection from accreting X-ray sources in general needs to be re-examined. For example, if an irradiated accretion disk existed in Mkn 509 at the time of the observations, the lack of spectral curvature above approximately 10 keV suggests two possibilities. Either the disk was Thomson-thick and highly ionized, having negligible Fe-K line emission and photoelectric absorption or the disk was Thomson-thin producing some or all of the broad Fe-K line emission. In the former case, the broad Fe-K line had to have produced in a Thomson-thin region elsewhere. In both cases the predicted spectral curvature above approximately 10 keV is negligible. An additional implication of our results is that any putative obscuring torus in the system, required by unification models of active galaxies, must also be Thomson-thin. The same applies to the optical broad line region (BLR) if it has a substantial covering factor.

Yaqoob, Tahir; Padmanabhan, Urmila; Kraemer, Steven B.; Crenshaw, D. Michael; Mckernan, Barry; George, Ian M.; Turner, T. Jane; White, Nicholas E. (Technical Monitor)

2002-01-01

191

Radiation from Excited Vortex in the Abelian  

Microsoft Academic Search

Excitation of a vortex in the Abelian Higgs model is investigated with the help of a polynomial approximation. The excitation can be regarded as a longitudinal component of the vector field trapped by the vortex. The energy and profile of the excitation are found. Back-reaction of the excitation on the vortex is calculated in the smalllimit. It turns out that

Higgs Model; H. Arodz; L. Hadas

192

Computer/Information Science  

ERIC Educational Resources Information Center

Scholars representing the field of computer/information science were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Ken Birman, Jennifer Rexford, Tim Roughgarden, Margo Seltzer, Jim Spohrer, and

Birman, Ken; Roughgarden, Tim; Seltzer, Margo; Spohrer, Jim; Stolterman, Erik; Kearsley, Greg; Koszalka, Tiffany; de Jong, Ton

2013-01-01

193

Science in Orbit  

NASA Technical Reports Server (NTRS)

This talk presents the excitement of doing science in space. It reviews some of the effects of the physical adaptations that the body undergoes to the lower gravity of space. It also discusses the role of the scientist in the space environment. It also discusses the potential uses of space development, particularly with the use of the space station.

Weber, Mary Ellen

2005-01-01

194

Excitation optimization for damage detection  

SciTech Connect

A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

Bement, Matthew T [Los Alamos National Laboratory; Bewley, Thomas R [UCSD

2009-01-01

195

Effects of dark atom excitations  

NASA Astrophysics Data System (ADS)

New stable quarks and charged leptons may exist and be hidden from detection, as they are bound by Coulomb interaction in neutral dark atoms of composite dark matter. This possibility leads to fundamentally new types of indirect effects related to the excitation of such dark atoms followed by their electromagnetic de-excitation. Stable -2 charged particles O--, bound to primordial helium in O-helium (OHe) atoms, represent the simplest model of dark atoms. Here we consider the structure of OHe atomic levels which is a necessary input for the indirect tests of such composite dark matter scenarios, and we give the spectrum of electromagnetic transitions from the levels excited in OHe collisions.

Cudell, Jean-Rene; Khlopov, Maxim Yu.; Wallemacq, Quentin

2014-11-01

196

J.T. Roberts' Science Fair  

NSDL National Science Digital Library

The following websites will be useful when preparing your science fair project. It is that time of year again! It is time to start planning your science fair project. All 7th and 8th grade students are required to participate in in the science fair. This is an opportunity to explore the exciting world in which we live. REQUIREMENTS: - Students will work ...

Ms. Greeley

2007-11-03

197

Engaging Students in Nuclear Physics Science Camp  

Microsoft Academic Search

Getting students interested in the sciences is a difficult task that all teachers face. Hope College Summer Science Camps aim to do just this by providing interesting topics to engage students of all ages with the hope that they become excited about science and school in general. In order to enthuse high school students about Physics as a possible career

Sarah Prill

2012-01-01

198

The exciting thing about recombinant DNA, Victor McElhenySite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

` Victor McElheny DNAi Location:Manipulation>Revolution>players>The controversy A new world of exploration Former science journalist Victor McElheny muses on the excitement that surrounded the new genetic technology.

2008-03-26

199

The suppression of exciting thoughts  

Microsoft Academic Search

We examined how the suppression of an exciting thought influences sympathetic arousal as indexed by skin conductance level (SCL). Subjects were asked to think aloud as they followed instructions to think about or not to think about various topics. Experiment l showed that trying not to think about sex, like thinking about sex, elevates SCL in comparison to thinking about

Daniel M. Wegner; Joann W. Shortt; Anne W. Blake; Michelle S. Page

1990-01-01

200

Perceptual Load Alters Visual Excitability  

ERIC Educational Resources Information Center

Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load

Carmel, David; Thorne, Jeremy D.; Rees, Geraint; Lavie, Nilli

2011-01-01

201

Elementary Excitations in Quantum Liquids.  

ERIC Educational Resources Information Center

Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)

Pines, David

1981-01-01

202

Backreaction of excitations on a vortex  

E-print Network

Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found in the cases of plane wave and wave packet type excitations. We find that the excited vortex radiates vector field and that the Higgs field has a very broad oscillating component.

Henryk Arodz; Leszek Hadasz

1996-07-15

203

Backreaction of excitations on a vortex  

E-print Network

Excitations of a vortex are usually considered in a linear approximation neglecting their backreaction on the vortex. In the present paper we investigate backreaction of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the backreaction corrections. Their approximate solutions are found in the cases of plane wave and wave packet type excitations. We find that the excited vortex radiates vector field and that the Higgs field has a very broad oscillating component.

Arodz, H; Arodz, Henryk; Hadasz, Leszek

1997-01-01

204

Science and Science Fiction  

ERIC Educational Resources Information Center

This article is for teachers looking for new ways to motivate students, increase science comprehension, and understanding without using the old standard expository science textbook. This author suggests reading a science fiction novel in the science classroom as a way to engage students in learning. Using science fiction literature and language

Oravetz, David

2005-01-01

205

SCIENCE CHINA Technological Sciences  

E-print Network

SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China; 2 Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000, China; 3 School of Material Science and Engineering, Georgia Institute

Wang, Zhong L.

206

NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective, a Deep  

E-print Network

NRC Earth Science Decadal Survey-Mission Concept Earth Sciences from the Astronomer's Perspective Irina Melnikova #12;1 Earth Sciences from the Astronomer's Perspective 1.0 Mission Concept and Purpose Earth observations from satellites located in deep space offer the exciting opportunity to look

Christian, Eric

207

Computer Science Teachers Association  

NSDL National Science Digital Library

The Computers Science Teachers Association (CSTA) is a professional organization that helps teachers in the field learn about professional development opportunities, along with offering them the opportunity to network. This section of then CSTA's website provides access to over a dozen helpful resources, including an instructional video and a college selection website. First-time visitors should check out the Quizzes with a Theme. Here they will find a set of computer science themed quizzes developed by Professor Bruce Maxwell of Colby College. Also, the CS Unplugged Videos area is quite a bit of fun. The videos here include a one-hour computer science show in which students encounter many concepts from computer science, along with short clips of activities that can be used in the classroom. Additionally, the site includes a selection of computer games designed for young women and a link to resources promoting excitement about computer science from Carnegie Mellon University.

208

Autoresonant excitation of dark solitons  

NASA Astrophysics Data System (ADS)

Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested.

Borich, M. A.; Shagalov, A. G.; Friedland, L.

2015-01-01

209

Autoresonant excitation of dark solitons.  

PubMed

Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

Borich, M A; Shagalov, A G; Friedland, L

2015-01-01

210

Tachyonic thermal excitations and causality  

E-print Network

We consider an ideal Fermi gas of tachyonic thermal excitations as a continuous medium and establish when it satisfies the causality condition. At high temperature the sound speed is always subluminal $c_stachyon matter below the critical temperature $T_ctachyon mass $m$. The pressure $P$ and energy density $E$ cannot be arbitrary small, but $P$ can exceed $E$, and $P=2.36E$ when $T\\rightarrow T_c$.

Ernst Trojan; George V. Vlasov

2011-10-08

211

Multiparticle excitations in 194Pb  

Microsoft Academic Search

High-spin states of 194Pb have been populated by the reaction 184W(16O,6n) at 113MeV beam energy and studied using the EUROGAM-1 array. The level scheme has been extended up to spin of 33? and excitation energy of 11.1MeV. The high-spin part of the level scheme is dominated by bands of dipole transitions. New dipole bands have been observed and the configurations

M. Kaci; M.-G. Porquet; I. Deloncle; M. Aiche; F. Azaiez; G. Bastin; C. W. Beausang; C. Bourgeois; R. M. Clark; R. Duffait; J. Duprat; B. J. P. Gall; F. Hannachi; K. Hauschild; M. J. Joyce; A. Korichi; Y. Le Coz; M. Meyer; E. S. Paul; N. Perrin; N. Poff; N. Redon; C. Schck; H. Sergolle; J. F. Sharpey-Schafer; J. Simpson; A. G. Smith; R. Wadsworth

2002-01-01

212

Electronic excitations in Guanine quadruplexes.  

PubMed

Guanine rich DNA strands, such as those encountered at the extremities of human chromosomes, have the ability to form four-stranded structures (G-quadruplexes) whose building blocks are guanine tetrads. G-quadruplex structures are intensively studied in respect of their biological role, as targets for anticancer therapy and, more recently, of their potential applications in the field of molecular electronics. Here we focus on their electronic excited states which are compared to those of non-interacting mono-nucleotides and those of single and double stranded structures. Particular emphasis is given to excited state relaxation processes studied by time-resolved fluorescence spectroscopy from femtosecond to nanosecond time scales. They include ultrafast energy transfer and trapping of ??* excitations by charge transfer states. The effect of various structural parameters, such as the nature of the metal cations located in the central cavity of G-quadruplexes, the number of tetrads or the conformation of the constitutive single strands, are examined. PMID:24563011

Changenet-Barret, Pascale; Hua, Ying; Markovitsi, Dimitra

2015-01-01

213

On Diversity of Configurations Generated by Excitable Cellular Automata with Dynamical Excitation Intervals  

NASA Astrophysics Data System (ADS)

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Adamatzky, Andrew

2012-11-01

214

Stable Manifolds as Thresholds for Multipulse Excitability  

E-print Network

(p) · · saddle case t· PA/BK/HO - Stable manifolds and excitability ­ p. #12;Excitable Systems and Homoclinic Bifurcations ·p Ws loc(p) Wu(p) · · saddle-focus (Shilnikov) case t· PA/BK/HO - Stable manifolds Communications 215 (2003) 367-379.] PA/BK/HO - Stable manifolds and excitability ­ p. #12;Excitable Systems

Doedel, Eusebius

215

Backreaction of excitations on a vortex  

Microsoft Academic Search

Excitations of a vortex are usually considered in a linear approximation neglect- ing their backreaction on the vortex. In the present paper we investigate backre- action of Proca type excitations on a straightlinear vortex in the Abelian Higgs model. We propose exact Ansatz for fields of the excited vortex. From initial set of six nonlinear field equations we obtain (in

Henryk Arodz; Leszek Hadas

216

Back reaction of excitations on a vortex  

Microsoft Academic Search

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we

Henryk Arodz; Leszek Hadasz

1997-01-01

217

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2014 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2014-10-01

218

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2013 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2013-10-01

219

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2012 CFR

...static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a residual-magnetism-type exciter that has the capability of voltage build-up after two months of no operation....

2012-10-01

220

The Astrophysics Science Division Annual Report 2009  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division (ASD) at Goddard Space Flight Center (GSFC) is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum - from gamma rays to radio wavelengths - as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions - WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contrast imaging techniques to search for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and support the astronomical community, and enable future missions by conceiving new concepts and inventing new technologies.

Oegerle, William (Editor); Reddy, Francis (Editor); Tyler, Pat (Editor)

2010-01-01

221

Goddard's Astrophysics Science Division Annual Report 2011  

NASA Technical Reports Server (NTRS)

The Astrophysics Science Division(ASD) at Goddard Space Flight Center(GSFC)is one of the largest and most diverse astrophysical organizations in the world, with activities spanning a broad range of topics in theory, observation, and mission and technology development. Scientific research is carried out over the entire electromagnetic spectrum from gamma rays to radiowavelengths as well as particle physics and gravitational radiation. Members of ASD also provide the scientific operations for three orbiting astrophysics missions WMAP, RXTE, and Swift, as well as the Science Support Center for the Fermi Gamma-ray Space Telescope. A number of key technologies for future missions are also under development in the Division, including X-ray mirrors, space-based interferometry, high contract imaging techniques to serch for exoplanets, and new detectors operating at gamma-ray, X-ray, ultraviolet, infrared, and radio wavelengths. The overriding goals of ASD are to carry out cutting-edge scientific research, and provide Project Scientist support for spaceflight missions, implement the goals of the NASA Strategic Plan, serve and suppport the astronomical community, and enable future missions by conceiving new conepts and inventing new technologies.

Centrella, Joan; Reddy, Francis; Tyler, Pat

2012-01-01

222

Band Excitation in Scanning Probe Microscopy: Sines of Change  

SciTech Connect

In three decades since Scanning Probe Microscopy (SPM) methods have entered scientific arena, they have become one of the main tool of nanoscale science and technology by offering the capability for imaging topography, magnetic, electrical, and mechanical properties on the nanometer scale. The vast majority of force-based SPM techniques to date are based on single-frequency sinusoidal excitation and detection. Here, we illustrate the intrinsic limitations of single-frequency detection that stem from the fundamental physics of dynamic systems. Consequently, many aspects of nanoscale materials functionality including quantitative mechanical, magnetic, and electrical measurements, probing dissipative interactions, to name a few remain unexplored. Band excitation is illustrated as a universal alternative to traditional single-frequency techniques that allows quantitative and reliable studies of dissipative and conservative phenomena, and can be universally applied to all ambient and liquid SPM methods.

Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

2011-01-01

223

Peculiarities of collisional excitation transfer with excited screened energy levels of atoms  

SciTech Connect

We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

Gerasimov, V. A. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Gerasimov, V. V. [Institute of Atmospheric Optics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation); Department of Physics, Tomsk State University, Tomsk, 634050 (Russian Federation); Pavlinskiy, A. V. [Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634055 (Russian Federation)

2007-09-15

224

Theoretical studies of electronically excited states  

SciTech Connect

Time-dependent density functional theory is the most widely used quantum chemical method for studying molecules in electronically excited states. However, excited states can also be computed within Kohn-Sham density functional theory by exploiting methods that converge the self-consistent field equations to give excited state solutions. The usefulness of single reference self-consistent field based approaches for studying excited states is demonstrated by considering the calculation of several types of spectroscopy including the infrared spectroscopy of molecules in an electronically excited state, the rovibrational spectrum of the NO-Ar complex, core electron binding energies and the emission spectroscopy of BODIPY in water.

Besley, Nicholas A. [School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (United Kingdom)

2014-10-06

225

Science and Science Fiction  

NSDL National Science Digital Library

This creative activity weaves science fiction and language arts skills into the science classroom, which can expand and enrich the science content and abstract concepts found in science textbooks.Well-written literature can be used to open new ways of learning and understanding while developing critical thinking skills for students of all abilities.

David Oravetz

2005-03-01

226

Turbulent swirling jets with excitation  

NASA Technical Reports Server (NTRS)

An existing cold-jet facility at NASA Lewis Research Center was modified to produce swirling flows with controllable initial tangential velocity distribution. Two extreme swirl profiles, i.e., one with solid-body rotation and the other predominated by a free-vortex distribution, were produced at identical swirl number of 0.48. Mean centerline velocity decay characteristics of the solid-body rotation jet flow exhibited classical decay features of a swirling jet with S - 0.48 reported in the literature. However, the predominantly free-vortex distribution case was on the verge of vortex breakdown, a phenomenon associated with the rotating flows of significantly higher swirl numbers, i.e., S sub crit greater than or equal to 0.06. This remarkable result leads to the conclusion that the integrated swirl effect, reflected in the swirl number, is inadequate in describing the mean swirling jet behavior in the near field. The relative size (i.e., diameter) of the vortex core emerging from the nozzle and the corresponding tangential velocity distribution are also controlling factors. Excitability of swirling jets is also investigated by exciting a flow with a swirl number of 0.35 by plane acoustic waves at a constant sound pressure level and at various frequencies. It is observed that the cold swirling jet is excitable by plane waves, and that the instability waves grow about 50 percent less in peak r.m.s. amplitude and saturate further upstream compared to corresponding waves in a jet without swirl having the same axial mass flux. The preferred Strouhal number based on the mass-averaged axial velocity and nozzle exit diameter for both swirling and nonswirling flows is 0.4.

Taghavi, Rahmat; Farokhi, Saeed

1988-01-01

227

Multipulse excitability in injected lasers  

NASA Astrophysics Data System (ADS)

We show that a single-mode semiconductor laser subject to optical injection, and described by rate equations, can produce excitable multipulses, where the laser emits a certain number of pulses after being triggered from its steady state by a single perturbation. This phenomenon occurs in experimentally accessible regions in parameter space that are bounded by curves of n-homoclinic bifurcations, connecting a saddle to itself only at the n-th return to a neighborhood of the saddle. These regions are organised in what we call 'homoclinic teeth' that grow in size and shape with the linewidth enhancement factor.

Krauskopf, Bernd; Wieczorek, Sebastian; Lenstra, Daan

2003-07-01

228

Electron impact excitation of methane  

NASA Technical Reports Server (NTRS)

A crossed molecular beam-electron beam apparatus was employed to examine the excitation cross-sections of CH4. Attention was given to 20, 30, and 200 eV impact energies at angles from 8-130 deg. Spectra were obtained in the elastic and inelastic realms as well as in the ionization continuum in the 12.99-15.0 eV energy-loss range. Differential cross-sections were also determined. The results are useful for modeling the behavior of CH4 in planetary atmospheres.

Vuskovic, L.; Trajmar, S.

1983-01-01

229

All that matters Exciting developments in the physical sciences  

E-print Network

/10/17/ive-got-you-under-my-skin/ #12;damage, and can be brought into almost any desirable shape you under my skin I've got you under my skin October 17, 2010 Joerg Heber Leave a comment Go Page 1 of 6I've got you under my skin « All that matters 10/25/2010http://blog.joerg.heber.name/2010

Rogers, John A.

230

CREDIT:PRESTONHUEY/SCIENCE hese are exciting times for supercon-  

E-print Network

even extend to room tempera- ture and beyond. The consequences for the low-temperature properties can in our understanding of new and exotic forms of superconductivity, and novel behavior is being discovered such as high pressure to tune the critical temperature of a phase transition toward absolute zero, producing

Grigera, Santiago

231

Dynamics of Excited Granular Systems  

NASA Astrophysics Data System (ADS)

Getting a hydrodynamic sort of behavior for excited granular systems is a delicate matter. In the case of ordinary (conservative) fluid systems the hydrodynamic limit is the limit of small Knudsen number. For granular systems such limit may lead to inconsistencies unless carefully performed. We present quite general gas-dynamic equations---derived from kinetic theory---which correctly describe highly excited granular systems. The theory describes a system of hard spheres (disks really) with normal restitution coefficient r and it requires no constitutive equations (dynamic equations take their place) [R. Ramirez, D. Risso, R. Soto, and P. Cordero, Phys. Rev. E 62, 2521 (2000); D. Risso, P. Cordero, Phys. Rev. E. 65 021304 (2002)]. Well known analytic results such as the presence of a fourth cumulant in the velocity distribution function are reproduced exactly. The formalism also predicts Bnard's type of convection triggerd by the granular temperature gradient that is dynamically created because of the inelastic nature of the collisons [R. Ramirez, D. Risso, and P. Cordero, Phys. Rev. Letters 85 1230 (2000); X. He, B. Meerson and G. Doolen, Phys. Rev. E 65 030301 (2002)]. A quasi-homogenoeus solution is also described in detail.

Cordero, Patricio; Risso, Dino

2002-08-01

232

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii ! If ) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If ) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga...

Diriken, J; Balabanski, D; Blasi, N; Blazhev, A; Bree, N; Cederkll, J; Cocolios, T E; Davinson, T; Eberth, J; Ekstrm, A; Fedorov, D V; Fedosseev, V N; Fraille, L M; Franchoo, S; Georgiev, G; Gladnishki, K; Huyse, M; Ivanov, O V; Ivanov, V S; Iwanicki, V; Jolie, J; Konstantinopoulos, T; Krll, Th; Krcken, R; Kster, U; Lagoyannis, A; Bianco, G Lo; Maierbeck, P; March, B A; Napiarkowski, P; Patronis, N; Pauwels, D; Reiter, P; Seliverstov, M; Sletten, G; Van de Walle, J; Van Duppen, P; Voulot, D; Walters, W B; Warr, N; Wenander, F; Wrzosek, K

2010-01-01

233

Coulomb excitation of 73Ga  

E-print Network

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

J. Diriken; I. Stefanescu; D. Balabanski; N. Blasi; A. Blazhev; N. Bree; J. Cederkll; T. E. Cocolios; T. Davinson; J. Eberth; A. Ekstrm; D. V. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. V. Ivanov; V. S. Ivanov; J. Iwanicki; J. Jolie; T. Konstantinopoulos; Th. Krll; R. Krcken; U. Kster; A. Lagoyannis; G. Lo Bianco; P. Maierbeck; B. A. Marsh; P. Napiorkowski; N. Patronis; D. Pauwels; P. Reiter; M. Seliverstov; G. Sletten; J. Van de Walle; P. Van Duppen; D. Voulot; W. B. Walters; N. Warr; F. Wenander; K. Wrzosek

2010-11-25

234

Dual excitation multiphase electrostatic drive  

SciTech Connect

A novel electrostatic drive technology named Dual Excitation Multiphase Electrostatic Drive (DEMED) was presented. A basic DEMED consisted of two plastic films in which 3-phase parallel electrodes were embedded and was driven by a 3-phase ac excitation to the electrodes. Static characteristics of DEMED were calculated and tested and the results agreed very well. Three prototype motors of DEMED were fabricated using commercially available technique. The first prototype consisted of a single slider and stator and generated a linear motion with a slider`s motion range of about 5mm. It weighed 7g and generated a power of 1.6W and a thrust force of 4.4N. The second prototype consisted of 50 layer stack of linear motors, summing their outputs. It weighed 3.6kg and generated a propulsive force of 310N being powered with boosted commercial 3-phase electricity. The third prototype consisted of a rotor and a stator in which electrodes were arranged radially and generated rotational motion. The maximum power of 36mW was generated by the prototype weighing only 260mg for its rotor and stator. From the results of the numerical calculation, a practical design methodology for the motor was determined. An optimal design for a motor employing currently available material and fabrication techniques is provided as an example. Analyses predict that force generation over the interfacial area between the slider and stator of this motor would be 3,900N/m{sup 2}.

Niino, Toshiki [Inst. of Physical and Chemical Research, Wako, Saitama (Japan); Higuchi, Toshiro [Univ. of Tokyo (Japan); [Kanagawa Academy of Science and Technology, Kawasaki, Kanagawa (Japan); Egawa, Saku [Hitachi Ltd., Tsuchiura, Ibaraki (Japan). Mechanical Engineering Research Lab.

1995-12-31

235

Laser-based excitation and diagnostics of planar fractures  

NASA Astrophysics Data System (ADS)

Faults are of interest not only to earth science, but also at different scales in the non-destructive testing (NDT) community. Remote sensing of faults is of interest to both communities, with the idea of inverting for the fracture properties in a non-invasive way. Alternatively, the wave field directly excited at the fracture is of interest to both communities because the waves thus radiated are equivalent to those emitted by acoustic emissions or micro-earthquakes. Much can be learned from recording of elastic waves excited at the the fracture. Based on technology developed for NDT, we use laser ultrasonics in the laboratory to excite and detect elastic waves, in order to determine the properties of fractures or faults in laboratory rock and synthetic samples. We show examples of wave propagation in a clear Poly(methyl methacrylate) cylinder. By focusing a high power infrared (IR) laser inside the cylinder we create a visible single disk-shaped fracture near the center of the sample. The laser generates a short pulse (~20 ns) of infrared light that is absorbed by the sample material at the focal point and is converted into heat. The sudden thermal expansion generates stress and forms a fracture parallel to the cylindrical axis. We excite elastic waves at the surface of the sample using the same high-power pulsed laser, but at a much lower energy setting, and with an unfocused beam. We measure the direct and scattered wave field from the fracture with a laser interferometer, and also excite the fracture directly with a fraction of the source laser energy impinging directly on the fracture. A comparison of the direct excitation and the elastic scattered wavefields, including studies of the tip diffractions from the fracture, shows strong agreement. The measured tip diffractions carry information about the stress concentration near the crack tips, which is crucial for understanding rupture processes. This novel laboratory technique allows us to measure the source radiation pattern under various conditions, and opens new possibilities for understanding earthquake dynamics and fracture dynamics, as a function of stress loads, local excitation of the fracture, and fluid content of fractures.

Blum, T. E.; Van Wijk, K.; Snieder, R.; Willis, M. E.

2011-12-01

236

Partnership in Science Education  

NSDL National Science Digital Library

This is an outline for an exchange of scientific and cultural information between high schools in different regions of the world. This activity outlines a recent exchange between a high school in New Hampshire and a high school in Guam. Scientific Exchange included: Acid Rain, Air Quality, Photo Essays of the Regions, Plant and Animal Comparisons, and Earth Science Studies. The Exchange proved to be an exciting collaboration for both schools.

Stephen Bartsch (Conval High School REV)

1995-06-30

237

MLCT excited states and charge delocalization in some ruthenium/ ammine/polypyridyl complexes  

E-print Network

MLCT excited states and charge delocalization in some rutheniumÁ/ ammineÁ/polypyridyl complexes in simple ammineÁ/polypyridineÁ/ruthenium(II) complexes. A gaussian analysis of the absorption and emission Science B.V. Keywords: AmmineÁ/polypyridineÁ/ruthenium(II) complexes; Vertical MLCT energy; Metal

Schlegel, H. Bernhard

238

Dear Camper Parent, The 2013 Physics Summer Camp is approaching and we are excited at the  

E-print Network

Dear Camper Parent, The 2013 Physics Summer Camp is approaching and we are excited at the prospect on this year's Science Summer Camp and registration forms. Please look over the contents of this packet: 2013 Physics Summer Camp c/o The University of Maine Department of Physics & Astronomy 5709 Bennett

Thomas, Andrew

239

Making Links between Maths and Science  

ERIC Educational Resources Information Center

For some children maths and science are exciting subjects that work side by side, one providing the opportunity to practise and hone skills and knowledge gained from the other. For other children the subjects are disjointed and seem to bear no relationship to each other. Science can provide a wonderful opportunity to practise a variety of math

Hiscock, Naomi

2012-01-01

240

Real-Life Maths and Science  

ERIC Educational Resources Information Center

As a primary teacher in a large junior school the author would spend many Sunday afternoons planning exciting science lessons only to find they did not include sufficient mathematical knowledge and skills. At the time, the Numeracy Strategy was spreading through classrooms like wildfire. Meanwhile, science lessons were progressing under the

Shields, Tanya

2012-01-01

241

Science literacy strategies anchored in nanotechnology  

Microsoft Academic Search

This article addresses teaching science using literacy (reading, writing, speaking, listening and viewing) strategies anchored in nanotechnology. Motivating students to learn complex scientific concepts such as atomic structure can be challenging, but using a modern context such as nanotechnology brings new excitement to learning the basic science knowledge. Nanoscience pedagogy presents unique literacy challenges because of the technical vocabulary and

David Devraj Kumar; Susanne I. Lapp; Philomena Marinaccio; Kimberly K. Scarola

2008-01-01

242

Hedgehog Excitations and their Superconducting Cores in the Antiferromagnetic State of SO(5) Materials  

NASA Astrophysics Data System (ADS)

Zhang's SO(5) approach to the physics of high-temperature superconducting materials(S.-C. Zhang, Science 275), 1089 (1997). contains the possibility that the antiferromagnetic state should support novel excitations that resemble antiferromagnetic hedgehogs at large distances but are predominantly superconducting inside a core region(P. M. Goldbart, Antiferromagnetic hedgehogs with superconducting cores); cond- mat/9711088 (UIUC Preprint P-97-10-030-iii).. Neither singular nor topologically stable, in contrast with their hedgehog cousins in pure antiferromagnetism, these excitations are what hedgehogs become when antiferromagnetic order is permitted to `` escape'' toward superconductivity---a central element in Zhang's approach. We describe the structure of antiferromagnetic hedgehog excitations with superconducting cores within the context of Zhang's approach to high-temperature superconducting materials, and touch upon a number of the experimental implications that these excitations engender.

Goldbart, Paul M.

1998-03-01

243

Entropy Driven Atomic Motion in Laser-Excited Bismuth  

NASA Astrophysics Data System (ADS)

We introduce a thermodynamical model based on the two-temperature approach in order to fully understand the dynamics of the coherent A1g phonon in laser-excited bismuth. Using this model, we simulate the time evolution of (111) Bragg peak intensities measured by Fritz et al. [Science 315, 633 (2007)SCIEAS0036-807510.1126/science.1135009] in femtosecond x-ray diffraction experiments performed on a bismuth film for different laser fluences. The agreement between theoretical and experimental results is striking not only because we use fluences very close to the experimental ones but also because most of the model parameters are obtained from ab initio calculations performed for different electron temperatures.

Giret, Y.; Gell, A.; Arnaud, B.

2011-04-01

244

Deconfined fractionally charged excitation in any dimensions  

SciTech Connect

An exact incompressible quantum liquid is constructed at the filling factor 1/m{sup 2} in the square lattice. It supports deconfined fractionally charged excitation. At the filling factor 1/m{sup 2}, the excitation has fractional charge e/m{sup 2}, where e is the electric charge. This model can be easily generalized to the n-dimensional square lattice (integer lattice), where the charge of excitations becomes e/m{sup n}. -- Highlights: ? We demonstrate that the fractionally-charged excitations can in principle exist in any dimensions. ? We compute the fractional charge of the excitations (e{sup ?}=e/m{sup D}). ? We demonstrate that the fractionally-charged excitation is in a deconfined phase.

Chern, Chyh-Hong, E-mail: chchern@ntu.edu.tw; Huang, Po-Hao; Lee, Hong-Hsi

2013-05-15

245

Photothermal excitation of microcantilevers in liquids  

NASA Astrophysics Data System (ADS)

We report the selective excitation of the flexural modes of microcantilevers in aqueous solutions, by applying the photothermal excitation technique. The experiments show that a particular vibration mode can be efficiently excited by focusing the intensity-modulated laser beam on regions of high curvature of the vibration shape. In addition, the resulting resonant peaks in liquid appear distorted by an amplitude component that decreases with the frequency. This distortion produces a shift of the resonance to lower frequencies. A theoretical model based on the transformation of optical energy into mechanical energy via an intermediate thermal stage is proposed to interpret the experimental results. The theory shows that the driven oscillation of the cantilever depends on the curvature of the eigenmode at the excitation position and the heating induced by the excitation laser, which decreases with the frequency. The results reported here set the basis for efficient excitation of high vibration modes in liquids and for optimized design of optically driven microresonators.

Ramos, D.; Tamayo, J.; Mertens, J.; Calleja, M.

2006-06-01

246

Back reaction of excitations on a vortex  

SciTech Connect

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component. {copyright} {ital 1997} {ital The American Physical Society}

Arodz, H.; Hadasz, L. [Jagellonian University, Institute of Physics, Reymonta 4, 30-059 Cracow (Poland)] [Jagellonian University, Institute of Physics, Reymonta 4, 30-059 Cracow (Poland)

1997-01-01

247

Back reaction of excitations on a vortex  

NASA Astrophysics Data System (ADS)

Excitations of a vortex are usually considered in a linear approximation neglecting their back reaction on the vortex. In the present paper we investigate back reaction of Proca-type excitations on a straight linear vortex in the Abelian Higgs model. We propose an exact ansatz for fields of the excited vortex. From an initial set of six nonlinear field equations we obtain (in a limit of weak excitations) two linear wave equations for the back reaction corrections. Their approximate solutions are found in the cases of plane wave and wave-packet-type excitations. We find that the excited vortex radiates the vector field and that the Higgs field has a very broad oscillating component.

Arod?, Henryk; Hadasz, Leszek

1997-01-01

248

Comparison of two-photon imaging depths with 775 nm excitation and 1300 nm excitation  

NASA Astrophysics Data System (ADS)

We quantitatively compared the maximal two-photon fluorescence microscopy imaging depth achieved with 775 nm excitation to that achieved with 1300 nm excitation through ex-vivo TPM of blood vessels in the mouse brain. We achieved high contrast imaging of labeled blood vessels at approximately twice the depth at 1300 nm excitation as at 775 nm excitation. We also measured the two-photon excitation cross-sections of several commercially available fluorophores at 1220-1320 nm. We found that some of these fluorophores reveal comparable if not better cross-section values than those of the widely used dyes excited by shorter wavelength light.

Kobat, Demirhan; Wong, Angela; Schaffer, Chris B.; Xu, Chris

2009-02-01

249

Supersymmetric approach to excited states.  

PubMed

We present here a supersymmetric (SUSY) approach for determining excitation energies within the context of a quantum Monte Carlo scheme. By using the fact that SUSY quantum mechanics gives rises to a series of isospectral Hamiltonians, we show that Monte Carlo ground-state calculations in the SUSY partners can be used to reconstruct accurately both the spectrum and states of an arbitrary Schrodinger equation. Since the ground state of each partner potential is nodeless, we avoid any "node" problem typically associated with the Monte Carlo technique. Although we provide an example of using this approach to determine the tunneling states in a double-well potential, the method is applicable to any 1D potential problem. We conclude by discussing the extension to higher dimensions. PMID:19919079

Bittner, Eric R; Maddox, Jeremy B; Kouri, Donald J

2009-12-31

250

Excited baryons in lattice QCD  

NASA Astrophysics Data System (ADS)

We present the first results for the masses of positive and negative parity excited baryons calculated in lattice QCD using an O(a2)-improved gluon action and a fat-link irrelevant clover (FLIC) fermion action in which only the irrelevant operators are constructed with APE-smeared links. The results are in agreement with earlier calculations of N* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner. A correlation matrix analysis reveals two low-lying JP=1/2- states with a small mass splitting. The study of different ? interpolating fields suggests a similar splitting between the lowest two ?1/2- octet states. However, the empirical mass suppression of the ?*(1405) is not evident in these quenched QCD simulations, suggesting a potentially important role for the meson cloud of the ?*(1405) and/or a need for more exotic interpolating fields.

Melnitchouk, W.; Bilson-Thompson, S.; Bonnet, F. D.; Hedditch, J. N.; Lee, F. X.; Leinweber, D. B.; Williams, A. G.; Zanotti, J. M.; Zhang, J. B.

2003-06-01

251

Coulomb excitation of 107Sn  

NASA Astrophysics Data System (ADS)

The radioactive isotope 107Sn was studied using Coulomb excitation at the REX-ISOLDE facility at CERN. This is the lightest odd-Sn nucleus examined using this technique. The reduced transition probability of the lowest-lying 3/2+ state was measured and is compared to shell-model predictions based on several sets of single-neutron energies relative to 100Sn . Similar to the transition probabilities for the 2+ states in the neutron-deficient even-even Sn nuclei, the measured value is underestimated by shell-model calculations. Part of the strength may be recovered by considering the ordering of the d_{5/2} and g_{7/2} single-neutron states.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekstrm, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhuser, R.; Grgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2012-07-01

252

Excited Baryons in Holographic QCD  

SciTech Connect

The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

2011-11-08

253

High-energy characteristics of the schizophrenic pulsar PSR J1846-0258?in Kes 75. Multi-year RXTE and INTEGRAL observations crossing the magnetar-like outburst  

NASA Astrophysics Data System (ADS)

Aims: PSR J1846-0258 is a young rotation-powered pulsar with one of the highest surface magnetic field strengths, located in the centre of SN-remnant Kes-75. In June 2006 a magnetar-like outburst took place. Using multi-year RXTE and INTEGRAL observations covering the epoch of the outburst, we aim to study the temporal and spectral characteristics of PSR J1846-0258 over a broad ~3-300 keV energy range to derive constraints on theoretical scenarios aiming to explain this schizophrenic behaviour. Methods: We explored all publically available RXTE observations of PSR J1846-0258 to generate accurate ephemerides over the period January 30, 2000-November 7, 2007. Phase-folding procedures yielded pulse profiles for RXTE PCA (~3-30 keV), RXTE HEXTE (~15-250 keV) and INTEGRAL ISGRI (~20-300 keV). The pulsed spectrum over the full ~3-300 keV energy range was derived, as well as the total spectrum (including the pulsar wind nebula) over the 20-300 keV band with the ISGRI. The timing, spatial, and spectral analyses were applied for epochs before, during, and after the magnetar-like outburst to study the evolution of the high-energy characteristics. Results: ISGRI detected PSR J1846-0258/Kes-75 before outburst during 2003-2006 with a power-law-shape spectrum over the 20-300 keV energy range with photon index ? = 1.800.06 and energy flux (20-300 keV) of (6.62 0.35) 10-11 erg/cm2 s. More than 90 days after the onset of the outburst, still during the decay phase, the same spectral shape was measured (? = 1.75-0.31+0.27) with an indication for a 52% (2.3?) enhanced total emission, while one year after the outburst the hard X-ray non-thermal emission of PSR J1846-0258/Kes-75 was found to be back to its pre-outburst values. PCA monitoring of PSR J1846-0258 before the outburst yielded phase-coherent ephemerides confirming the earlier derived breaking index of the spindown. During the outburst, incoherent solutions have been derived. We show that the radiative outburst was triggered by a major spin-up glitch near MJD 53 883 3 with a glitch size ??/? in the range (2.0-4.4) 10-6. Using all pre-outburst observations of ISGRI and HEXTE for the first time pulse profiles have been obtained up to 150 keV with a broad single asymmetric pulse. The pulse shape did not vary with energy over the 2.9-150 keV energy range, nor did it change during the magnetar-like outburst. The time-averaged pre-outburst ~3-300 keV pulsed spectrum measured with the PCA, HEXTE, and ISGRI was fitted with a power-law model with ? = 1.20 0.01. A fit with a curved power-law model gives an improved fit. Around 150 keV the pulsed fraction approaches 100%. For the first 32 days of the magnetar-like outburst, the 3-30 keV pulsed spectrum can be represented with two power laws, a soft component with index ?s = 2.96 0.06 and a hard component with the pre-outburst value ?h 1.2. Above ~9 keV, all spectra during outburst are consistent with the latter single power-law shape with index ~1.2. The 2-10 keV flux increased by a factor ~5 and the 10-30 keV flux increased with only 35%. After ~120 days the soft outburst and the enhancement of the hard non-thermal component both vanish. Conclusions: The varying temporal and spectral characteristics of PSR J1846-0258 can be explained in a scenario of a young high-B-field pulsar in which a major glitch triggered a sudden release of energy. Resonant cyclotron upscattering could subsequently generate the decaying/cooling soft pulsed component measured during outburst between 3 and 10 keV. The (variation in the) non-thermal hard X-ray component can be explained with synchrotron emission in a slot-gap or outer-gap pulsar model.

Kuiper, L.; Hermsen, W.

2009-07-01

254

Vibrationally Excited C4H  

NASA Astrophysics Data System (ADS)

Rotational spectra in four new excited vibrational levels of the linear carbon chain radical C4H were observed in the millimeter band between 69 and 364 GHz in a low pressure glow discharge, and two of these were observed in a supersonic molecular beam between 19 and 38 GHz. All have rotational constants within 0.4% of the {{X}2}{{{? }}+} ground vibrational state of C4H and were assigned to new bending vibrational levels, two each with 2{? } and 2{\\Pi } vibrational symmetry. The new levels are tentatively assigned to the 1{{? }6} and 1{{? }5} bending vibrational modes (both with 2{\\Pi } symmetry), and the 1{{? }6}+1{{? }7} and 1{{? }5}+1{{? }6} combination levels (2{? } symmetry) on the basis of the derived spectroscopic constants, relative intensities in our discharge source, and published laser spectroscopic and quantum calculations. Prior spectroscopic constants in the 1{{? }7} and 2{{? }7} levels were refined. Also presented are interferometric maps of the ground state and the 1{{? }7} level obtained with the Submillimeter Array (SMA) near 257 GHz which show that C4H is present near the central star in IRC+10216. We found no evidence with the SMA for the new vibrationally excited levels of C4H at a peak flux density averaged over a 3\\prime\\prime synthesized beam of ?slant 0.15 Jy/beam in the 294-296 and 304-306 GHz range, but it is anticipated that rotational lines in the new levels might be observed in IRC+10216 when ALMA attains its full design capability.

Cooksy, Andrew L.; Gottlieb, C. A.; Killian, T. C.; Thaddeus, P.; Patel, Nimesh A.; Young, Ken H.; McCarthy, M. C.

2015-02-01

255

Collisional energy transfer from excited nitrogen dioxide  

NASA Astrophysics Data System (ADS)

The radiative lifetimes of gaseous nitrogen dioxide excited by pulsed, tunable dye laser radiation are determined for excitation wavelengths ranging from 400 to 750 nm. When the data are expressed in the form of zero-pressure radiative rate constants (k(sub 0)/s exp -1), they fit a linear equation with respect to excitation energy. This fit predicts a radiative lifetime of 64 microseconds for 400 nm excitation and 102 microseconds at 750 nm. The effects of pressure, observation delay time, and wavelength range of the fluorescence detection apparatus are determined for both radiative lifetime and quenching constant. Dispersed fluorescence spectra from excited nitrogen dioxide are analyzed into three-parameter functions that approximate the corresponding excited state population distributions. Energy transfer from nitrogen dioxide excited at 532 nm and colliding with thirteen buffer gases is studied by this population deconvolution method. The energy removal rate constants increase in the order Ne, Ar, Kr, Xe, He, CO, N2, O2, NO, NO2, CO2, SF6, SO2. The energy transfer rate constant is strongly correlated with the number of degrees of freedom of the buffer molecule and with low vibrational frequencies of the buffer molecule. Population deconvolution from excited nitrogen dioxide fluorescence spectra is again employed to find energy removal rate constants for the NO2*-NO2 collisions, excited by dye laser at 475.34, 435.04, and 400.00 nm. The energy transfer rate constant increases with decreasing excitation wavelength. The energy removal rate constant between 400 and 532 nm excitation increases as the (3.6 +/- 0.4) power of the excitation photon energy.

Patten, K. O.

1991-05-01

256

Photobleaching in Two-Photon Excitation Microscopy  

Microsoft Academic Search

The intensity-squared dependence of two-photon excitation in laser scanning microscopy restricts excitation to the focal plane and leads to decreased photobleaching in thick samples. However, the high photon flux used in these experiments can potentially lead to higher-order photon interactions within the focal volume. The excitation power dependence of the fluorescence intensity and the photobleaching rate of thin fluorescence samples

George H. Patterson; David W. Piston

2000-01-01

257

Gluonic excitations in the hadronic spectrum  

NASA Astrophysics Data System (ADS)

I describe progress made by the Hadron Spectrum Collaboration in understanding the role that excitations of the gluonic field play in determining the spectrum of hadrons. This is achieved through calculations of the hadron spectrum using lattice QCD techniques. Clear signals for the lightest set of hybrid mesons and baryons are presented, and a proposal that they correspond to the same chromomagnetic excitation is made. The prospects for studying the decay properties of excited hadrons are briefly discussed.

Dudek, Jozef

2014-06-01

258

Excitable Optical Waves in Semiconductor Microcavities  

NASA Astrophysics Data System (ADS)

We demonstrate experimentally and theoretically the existence of excitable optical waves in semiconductor microcavities. Although similar to those observed in biological and chemical systems, these excitable optical waves are self-confined. This is due to a new dynamical scenario, where a stationary Turing pattern controls the propagation of waves in an excitable medium, thus bringing together the two paradigms of dynamical behavior (waves and patterns) in active media.

Marino, Francesco; Balle, Salvador

2005-03-01

259

Design evaluation: S-band exciters  

NASA Technical Reports Server (NTRS)

A design evaluation study was conducted to produce S-band exciter (SBE) system to provide a highly stable phase or modulated carrier for transmission to spacecraft. The exciter is part of an S-band receiver/exciter/ranging system at Spaceflight Tracking and Data Network (STDN) ground stations. The major features of the system are defined. Circuit diagrams of the electronic components are provided.

1974-01-01

260

Science in Science Fiction.  

ERIC Educational Resources Information Center

Offers some suggestions as to how science fiction, especially television science fiction programs such as "Star Trek" and "Star Wars", can be drawn into physics lessons to illuminate some interesting issues. (Author/KHR)

Allday, Jonathan

2003-01-01

261

Ground and Excited State Spectra of a Quantum Dot  

NASA Astrophysics Data System (ADS)

We present linear and nonlinear magnetoconductance measurements of the ground and excited state spectra for successive electron occupancy in a gate defined lateral quantum dot. Previous measurementsfootnote D.R. Stewart, D. Sprinzak, C.M. Marcus, C.I. Duruoz and J.S. Harris Jr., Science 278, (1997). showed a direct correlation between the mth excited state of the N-electron system and the ground state of the (N+m)-electron system for m up to 4, consistent to a large degree with a single-particle picture. Here we report quantitative deviations of the excited state spectra from the spectrum of ground state magnetoconductances, attributed to many-body interactions in the finite system of N ~200 electrons. We also describe the behaviour of anticrossings in the ground state magnetoconductances. We acknowledge the support of JSEP (DAAH04-94-G-0058), ARO (DAAH04-95-1-0331), ONR-YIP (N00014-94-1-0622) and the NSF-PECASE program. D.S. acknowledges the support of MINERVA grant.

Stewart, D. R.; Sprinzak, D.; Patel, S. R.; Marcus, C. M.; Duruoz, C. I.; Harris, J. S.

1998-03-01

262

Quasiparticle excitations in superdeformed [sup 192]Hg  

SciTech Connect

For the first time, two excited superdeformed (SD) bands have been observed in the double closed shell superdeformed nucleus [sup 192]Hg. One of the SD bands exhibits a pronounced peak in the dynamic moment of inertia which is interpreted as a crossing between two excited SD configurations involving the [ital N]=7 intruder and the [512]5/2 orbitals. This is only the second occurrence of such a crossing in a SD nucleus around [ital A]=190. The second excited SD band has near identical transition energies to an excited SD band in [sup 191]Hg.

Fallon, P. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Lauritsen, T.; Ahmad, I.; Carpenter, M.P. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Cederwall, B.; Clark, R.M. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Crowell, B. (Argonne National Labortory, Argonne, Illinois 60439 (United States)); Deleplanque, M.A.; Diamond, R.M. (Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Gall, B.; Hannachi, F. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, IN2P-CNRS bat 104-108, F-91405 Orsay Cedex (France)); Henry, R.G.; Janssens, R.V.F.; Khoo, T.L. (Argonne National Laboratory, Argonne, Illinois 60439 (United States)); Korichi, A. (Institut de Physique Nucleaire, IN2P3-CNRS bat 104, F-91406 Orsay Cedex (France)); Lee, I.Y.; Macchiavelli, A.O. (Nuclear Science Division, Lawrence

1995-04-01

263

FORENSIC SCIENCE About Forensic Science  

E-print Network

Fact Sheet FORENSIC SCIENCE About Forensic Science: The Forensic Science program at SJSU offers: The SJSU Forensic Science program delivers coursework and training to Empowergraduatestobecomeagentsofchangetorecognize, document and report errors and injustices in the practice of forensic science and crime scene

Su, Xiao

264

Pharmacology SchoolofMedicalSciences  

E-print Network

BSc (Hons) Immunology and Pharmacology Degree Programme Guide 2014-15 SchoolofMedicalSciences #12 and chronic inflammatory diseases. Immunology with pharmacology is therefore concerned primarily. The degree of Immunology & Pharmacology at Aberdeen is an exciting and original new programme which

Levi, Ran

265

Reproducible Research in Computational Science  

PubMed Central

Computational science has led to exciting new developments, but the nature of the work has exposed limitations in our ability to evaluate published findings. Reproducibility has the potential to serve as a minimum standard for judging scientific claims when full independent replication of a study is not possible. PMID:22144613

Peng, Roger D.

2012-01-01

266

Reproducible research in computational science.  

PubMed

Computational science has led to exciting new developments, but the nature of the work has exposed limitations in our ability to evaluate published findings. Reproducibility has the potential to serve as a minimum standard for judging scientific claims when full independent replication of a study is not possible. PMID:22144613

Peng, Roger D

2011-12-01

267

SCIENCE CHINA Technological Sciences  

E-print Network

SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg. Density-functional-theory formulation of classical and quantum Hooke's law. Sci China Tech Sci, 2014, 57- sider an equilibrium lattice without strain (=0), but elec- #12;Hu H, et al. Sci China Tech Sci April

Simons, Jack

268

Literacy and Secondary Science--Building on Primary Experience.  

ERIC Educational Resources Information Center

Provides an insight into the scope and practice of Literacy Strategy which encourages primary children in England to read and write non-fiction more effectively, the way it is being used to complement primary science, and how it provides secondary science teachers with an exciting opportunity to improve pupil achievement in science. (Contains 18

McKeon, Frankie

2000-01-01

269

UNIVERSITY OF FLORIDA DEPARTMENT OF ENVIRONMENTAL ENGINEERING SCIENCES  

E-print Network

1 1/2013 UNIVERSITY OF FLORIDA DEPARTMENT OF ENVIRONMENTAL ENGINEERING SCIENCES GRADUATE STUDENT GUIDELINES Welcome to the Department of Environmental Engineering Sciences at UF! We are excited you of Environmental Engineering Sciences. Academic requirements cited in this document may be more stringent than

Slatton, Clint

270

Teaching Basic Communication Science Concepts Through a Guided Literature Review.  

ERIC Educational Resources Information Center

Students in introductory classes in communication research methodology are told several basic concepts; science is cumulative; science is self-correcting; empirical controversies are resolvable; and science is creative and exciting. However, unless evidence in the form of empirical data is presented to support these assertions, most students fail

Hocking, John E.; Miller, M. Mark

271

Science Highlights from the Spitzer Legacy Program  

NASA Astrophysics Data System (ADS)

The original Spitzer Legacy Science Program is returning a wide array of science results, ranging from star formation in the Milky Way and nearby galaxies to the most distant reaches of the Universe. We present highlights of exciting science results that have appeared in the literature and press releases over the past year from the C2D, FEPS, GLIMPSE, GOODS, SINGS and SWIRE Legacy teams.

Storrie-Lombardi, L.; Jarrett, T.; Squires, G.

2005-12-01

272

Electron excitation energy transfer from highly excited Cs atoms forming high Rydberg state atoms and molecules  

Microsoft Academic Search

The reactions of excited Cs atoms with various gases have been studied in a quadrupole mass spectrometer ion source. The excited atoms are formed in a thermionic converter (TIC) plasma and are sampled into the ion source as a molecular beam. Direct field ionization of the excited states from the plasma at field strengths up to 600 V\\/cm in the

Joergen Lundin; Leif Holmlid

1991-01-01

273

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media  

E-print Network

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media Statics#25; (#(~r) + !t)) #12; #12; #12; #12; #26;!+1 ; (2) where #26;(~r) and #(~r) are the polar coordinates the same kind of meander #12; NL3451 Vortex dynamics in excitable media 2 (a) (b) (c) (d) Figure 1. Typical

Biktashev, Vadim N.

274

Excited-state wavepacket and potential reconstruction by coherent anti-Stokes Raman scattering.  

PubMed

Among the major challenges in the chemical sciences is controlling chemical reactions and deciphering their mechanisms. Since much of chemistry occurs in excited electronic states, in the last three decades scientists have employed a wide variety of experimental techniques and theoretical methods to recover excited-state potential energy surfaces and the wavepackets that evolve on them. These methods have been partially successful but generally do not provide a complete reconstruction of either the excited state wavepacket or potential. We have recently proposed a methodology for reconstructing excited-state molecular wavepackets and the corresponding potential energy surface [Avisar and Tannor, Phys. Rev. Lett., 2011, 106, 170405]. In our approach, the wavepacket is represented as a superposition of the set of vibrational eigenfunctions of the molecular ground-state Hamiltonian. We assume that the multidimensional ground-state potential surface is known, and therefore these vibrational eigenfunctions are known as well. The time-dependent coefficients of the basis functions are obtained by experimental measurement of the resonant coherent anti-Stokes Raman scattering (CARS) signal. Our reconstruction strategy has several significant advantages: (1) the methodology requires no a priori knowledge of any excited-state potential. (2) It applies to dissociative as well as to bound excited-state potentials. (3) It is general for polyatomics. (4) The excited-state potential surface is reconstructed simultaneously with the wavepacket. Apart from making a general contribution to the field of excited-state spectroscopy, our method provides the information on the excited-state wavepacket and potential necessary to design laser pulse sequences to control photochemical reactions. PMID:25119931

Avisar, David; Tannor, David J

2015-01-28

275

Excited State Processes in Photosynthesis Molecules  

Microsoft Academic Search

A study of electronic processes in the chlorophyll and carothenoid molecules of the photo-reaction center II is presented with the focus on the electronic excitations and charge transfer in the photosynthetic process. Several novel ideas are mentioned especially concerning the electron replenishment and nuclear vibrational excitations. The study is build mainly on numerical quantum calculations of electronic structures of molecules

Henrik Bohr; Per Greisen; Barry Malic

2008-01-01

276

Excited State Processes in Photosynthesis Molecules  

Microsoft Academic Search

A study of electronic processes in the chlorophyll and carothenoid molecules of the photoreaction center II is presented with the focus on the electronic excitations and charge transfer in the photosynthetic process. Several novel ideas are mentioned especially concerning the electron replenishment and nuclear vibrational excitations. The study is build mainly on numerical quantum calculations of electronic structures of molecules

Henrik Bohr; Per Greisen; Barry Malic

2009-01-01

277

Are axoplasmic microtubules necessary for membrane excitation?  

Microsoft Academic Search

Summary The excitability of the squid giant axon was studied as a function of transmembrane hydrostatic pressure differences, the latter being altered by the technique of intracellular perfusion. When a KF solution was used as the internal medium, a pressure difference of about 15 cm water had very little effect on either the membrane potential or excitability. However, within a

Susumu Terakawa; Takashi Nakayama

1985-01-01

278

Surface and bulk excitations in condensed matter  

Microsoft Academic Search

In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept

Ritchie

1988-01-01

279

Excitation energy migration dynamics in upconversion nanomaterials.  

PubMed

Recent efforts and progress in unraveling the fundamental mechanism of excitation energy migration dynamics in upconversion nanomaterials are covered in this review, including short- and long-term interactions and other interactions in homogeneous and heterogeneous nanostructures. Comprehension of the role of spatial confinement in excitation energy migration processes is updated. Problems and challenges are also addressed. PMID:25223635

Tu, Langping; Liu, Xiaomin; Wu, Fei; Zhang, Hong

2015-03-10

280

Study of excited nucleons and their structure  

SciTech Connect

Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.

Burkert, Volker D. [JLAB, Newport News, VA (United States)

2014-01-01

281

What Gets a Cell Excited? Kinky Curves  

ERIC Educational Resources Information Center

Hodgkin and Huxley's (5) revealing the origins of cellular excitability is one of the great triumphs of physiology. In an extraordinarily deft series of papers, they were able to measure the essential electrical characteristics of neurons and synthesize them into a quantitative model that accounts for the excitability of neurons and other

Kay, Alan R.

2014-01-01

282

131Cognitive Science COGNITIVE SCIENCE  

E-print Network

131Cognitive Science COGNITIVE SCIENCE PROFESSOR ELMES* MAJOR A major in cognitive science leading courses: Cognitive Science 110, 395, 403, 473; Computer Science 111, 211; Philosophy 106, 313; Psychology Science: Com- puter Science 295 (LISP, PROLOG or C), 313, 315; Psychology 207 b. Philosophical Foundations

Marsh, David

283

NASA Science Served Family Style  

NASA Astrophysics Data System (ADS)

Family oriented innovative programs extend the reach of many traditional out-of-school venues to involve the entire family in learning in comfortable and fun environments. Research shows that parental involvement is key to increasing student achievement outcomes, and family-oriented programs have a direct impact on student performance. Because families have the greatest influence on children's attitudes towards education and career choices, we have developed a Family Science program that provides families a venue where they can explore the importance of science and technology in our daily lives by engaging in learning activities that change their perception and understanding of science. NASA Family Science Night strives to change the way that students and their families participate in science, within the program and beyond. After three years of pilot implementation and assessment, our evaluation data shows that Family Science Night participants have positive change in their attitudes and involvement in science.  Even after a single session, families are more likely to engage in external science-related activities and are increasingly excited about science in their everyday lives.  As we enter our dissemination phase, NASA Family Science Night will be compiling and releasing initial evaluation results, and providing facilitator training and online support resources. Support for NASA Family Science Nights is provided in part through NASA ROSES grant NNH06ZDA001N.

Noel-Storr, Jacob; Mitchell, S.; Drobnes, E.

2010-01-01

284

Science Poetry in Two Voices: Poetry and the Nature of Science  

ERIC Educational Resources Information Center

Poetry can be used during science instruction to foster interest, excitement, and wonder among elementary-level students. Children can read poetry, or have poetry read to them, as a way of learning about their world. They can also create poems to share their own science learning with others. We introduce two formats of the Poetry in Two Voices

Frazier, Wendy M.; Murray, Kristen B.

2009-01-01

285

Statement by Dr. Raymond L. Orbach Under Secretary for Science and Director, Office of Science  

E-print Network

Statement by Dr. Raymond L. Orbach Under Secretary for Science and Director, Office of Science U.S. Department of Energy May 22, 2008 Future of the Princeton Plasma Physics Laboratory (PPPL) In late 2006 an exciting path for PPPL research well into the future. Following several internal and external reviews over

286

Science and Science Fiction  

SciTech Connect

I will explore the similarities and differences between the process of writing science fiction and the process of 'producing' science, specifically theoretical physics. What are the ground rules for introducing unproven new ideas in science fiction, and how do they differ from the corresponding rules in physics? How predictive is science fiction? (For that matter, how predictive is theoretical physics?) I will also contrast the way in which information is presented in science fiction, as opposed to its presentation in scientific papers, and I will examine the relative importance of ideas (as opposed to the importance of the way in which these ideas are presented). Finally, I will discuss whether a background as a research scientist provides any advantage in writing science fiction.

Scherrer, Robert (Vanderbilt University) [Vanderbilt University

2006-03-29

287

The Excitation of Sodium by Ionized Mercury Vapor  

Microsoft Academic Search

Excitation of sodium by excited and by ionized mercury vapor.-The excitation of the sodium spectrum by ionized mercury distilling from an arc was studied in a tube in which conditions were under control. An auxiliary electrode in the stream of mercury vapor was used to increase the number of excited atoms at the point of observation until the excitation due

Harold W. Webb; S. C. Wang

1929-01-01

288

Collision Frequency of Molecules Excited by Monochromatic Light  

Microsoft Academic Search

The variation in intensity of the exciting line across the absorption line in fluorescence spectra excited by monochromatic light is shown to result in a non-Maxwellian velocity distribution of the excited molecules. Expressions for the collision frequency and velocity distribution of the excited molecules are derived, assuming that the fluorescence exciting line is Gaussian and that the absorption line is

Ralph H. Kummler; M. McCarty Jr.

1965-01-01

289

Science as Performance: A Proactive Strategy to Communicate and Educate Through Theater, Music and Dance  

Microsoft Academic Search

Theater, music, dance, the literary and the visual arts can convey the joys and controversies of science. We describe a program at the Graduate Center entitled Science as Performance which is designed to communicate to the public the excitement and wonder of science, technology, engineering and mathematics. Over the past few years there have been major successes in communicating science

Brian Schwartz

2006-01-01

290

Inclusion, Disabilities, and Informal Science Learning. A CAISE Inquiry Group Report  

ERIC Educational Resources Information Center

Informal science education (ISE) experiences can provide powerful opportunities for people with disabilities to experience and learn about science. When designed to be inclusive, such experiences can lead people with disabilities to feel competent and empowered as science learners, generate excitement and enthusiasm for science, and be equitable

Reich, Christine; Price, Jeremy; Rubin, Ellen; Steiner, Mary Ann

2010-01-01

291

Inclusion, Disabilities, and Informal Science Learning. A CAISE Inquiry Group Report. Executive Summary  

ERIC Educational Resources Information Center

Informal science education (ISE) experiences can provide powerful opportunities for people with disabilities to experience and learn about science. When designed to be inclusive, such experiences can lead people with disabilities to feel competent and empowered as science learners, generate excitement and enthusiasm for science, and be equitable

Center for Advancement of Informal Science Education, 2010

2010-01-01

292

Alabama Computer Science Summer Camps (commuter and dorm-based options)  

E-print Network

Alabama Computer Science Summer Camps (commuter and dorm-based options) Overview of Summer Camps The University of Alabama Department of Computer Science will host a series of computer science camps in Summer a computer in several exciting contexts (robotics control and smartphone apps). The Computer Science Camps

Carver, Jeffrey C.

293

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of 5106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for ? -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( ? L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ? value for 21Na is 1379 e^2fm^4, while the resulting B( ? L) ? values for 20Na are 556 e^2fm^4 for the 3+ rightarrow 2+ , 35.75.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.1540.030 ?_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( ? L) values for the proton dripline nucleus 20Na .-1

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-12-01

294

Science Mathematics Engineering  

E-print Network

Science Mathematics Engineering . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, . ­ p.1 #12;Science Mathematics Engineering Science, Computer `Science', Mathematics, and Software Development

Hamlet, Richard

295

Practicing Science: The Investigative Approach in College Science Teaching  

NSDL National Science Digital Library

In this collection of ten articles reprinted from the Journal of College Science Teaching, college and university science professors show how they have used investigative learning--or inquiry-based instruction--to introduce students to the process of science. These first-person accounts demonstrate how students, including non-science majors, can learn to do science as it is done in the real world--through hypothesis building, observation, and experimental design. The higher education faculty represented in this book is committed to the investigative approach. As one contributor writes, "Would I return to lecturing in a traditional fashion? Not a chance. The excitement and energy of a room of students working in groups, challenging each other, and questioning each other is what I'll always want to see in my classroom."

NSTA Press

2001-01-01

296

Relativistic dynamical spin excitations of magnetic adatoms  

NASA Astrophysics Data System (ADS)

We present a first-principles theory of dynamical spin excitations in the presence of spin-orbit coupling. The broken global spin rotational invariance leads to a new sum rule. We explore the competition between the magnetic anisotropy energy and the external magnetic field, as well as the role of electron-hole excitations, through calculations for 3 d -metal adatoms on the Cu(111) surface. The spin excitation resonance energy and lifetime display nontrivial behavior, establishing the strong impact of relativistic effects. We legitimate the use of the Landau-Lifshitz-Gilbert equation down to the atomic limit, but with parameters that differ from a stationary theory.

dos Santos Dias, M.; Schweflinghaus, B.; Blgel, S.; Lounis, S.

2015-02-01

297

Spin excitations in di-nuclear systems  

SciTech Connect

The spin excitations of products from two-body reactions have two sources: transfer of orbital motion into intrinsic spins via tangential friction and thermal excitations of di-nuclear spin modes. The relative importance of these two mechanisms is discussed for deep inelastic scattering, quasi-fission and spontaneous fission processes. The results of simple model calculations are compared to measured {gamma}-multiplicities in {sup 238}U induced quasi-fission reactions and it is concluded that the spin-excitation are only partially equilibrated during the interaction. 11 refs., 5 figs.

Back, B.B.

1990-01-01

298

Pulse Vector-Excitation Speech Encoder  

NASA Technical Reports Server (NTRS)

Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.

Davidson, Grant; Gersho, Allen

1989-01-01

299

Surface and bulk excitations in condensed matter  

SciTech Connect

In this lecture collective and single-particle electron excitations of solids will be discussed with emphasis on the properties of metallic and semiconducting materials. However, some of the general properties of long-wavelength collective modes to be discussed are valid for insulators as well, and some considerations apply to nuclear excitations such as optical or acoustical phonons, dipolar plasmons, etc. The concept of elementary excitations in solids, pioneered by Bohm and Pines almost 4 decades ago, has proved to be extremely useful in understanding the properties of systems of many particles, especially in respect to the response to the action of external probes. 32 refs., 12 figs.

Ritchie, R.H.

1988-01-01

300

First Evidence of Double Spin Isospin Excitation  

NASA Astrophysics Data System (ADS)

To study double spin-isospin responses in view of the ??0? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher ?L excitations.

Takahisa, Keiji

2007-06-01

301

First Evidence of Double Spin Isospin Excitation  

SciTech Connect

To study double spin-isospin responses in view of the {beta}{beta}0{nu} decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher {delta}L excitations.

Takahisa, Keiji [Research Center for Nuclear Physics, Osaka University, Mihogaoka 10-1, Ibaraki, Osaka, 567-0047 (Japan)

2007-06-13

302

Helicon wave excitation with helical antennas  

NASA Astrophysics Data System (ADS)

Components of the wave magnetic field in a helicon discharge have been measured with a single-turn, coaxial magnetic probe. Left- and right-handed helical antennas, as well as plane-polarized antennas, were used; and the results were compared with the field patterns computed for a nonuniform plasma. The results show that the right-hand circularly polarized mode is preferentially excited with all antennas, even those designed to excite the left-hand mode. For right-hand excitation, the radial amplitude profiles are in excellent agreement with computations.

Light, Max; Chen, Francis F.

1995-04-01

303

Electron-impact excitation of holmium atoms  

SciTech Connect

The electron-impact excitation of holmium atoms was studied by the method of extended crossing beams. The cross sections and the optical excitation functions were obtained for odd levels of Ho I, including the 22014 cm{sup -1} laser level. Over 99% of the atoms were shown to reside in the ground level prior to collisions with electrons. Also measured were the excitation cross sections for six even levels, which presumably participate in the formation of inversion population in a gas-discharge holmium vapour laser. (laser applications and other topics in quantum electronics)

Smirnov, Yu M [Moscow Power Engineering Institute, Moscow (Russian Federation)

2000-06-30

304

Faculty of Science: EARTH SCIENCES  

E-print Network

Faculty of Science: EARTH SCIENCES Possible Careers Geologist Geochemist Geophysicist Mining - www.gac.ca Canadian Federation of Earth Sciences - www.geoscience.ca Canadian Geotechnical Society Engineer Glaciologist Science-Based Investment Advisor Environmental Consultant Land Surveyor Environmental

Brownstone, Rob

305

Science Sampler: Making movies in the classroom  

NSDL National Science Digital Library

When you overhear students talking excitedly about video games, the internet, television, or movies, do you ever wish that they could get that excited about what was happening in the science classroom? By using simple software, students can plan, shoot, and edit movies of their own design! In this fascinating activity, students create a documentary on a famous earthquake, volcanic eruption, tsunami, hurricane, or other natural disaster as they put their own unique spin on the theory of plate tectonics.

Lauren Richards

2006-07-01

306

Excited state dynamics and isomerization in ruthenium sulfoxide complexes.  

PubMed

Molecular photochromic compounds are those that interconvert between two isomeric forms with light. The two isomeric forms display distinct electronic and molecular structures and must not be in equilibrium with one another. These light-activated molecular switch compounds have found wide application in areas of study ranging from chemical biology to materials science, where conversion from one isomeric form to another by light prompts a response in the environment (e.g., protein or polymeric material). Certain ruthenium and osmium polypyridine sulfoxide complexes are photochromic. The mode of action is a phototriggered isomerization of the sulfoxide from S- to O-bonded. The change in ligation drastically alters both the spectroscopic and electrochemical properties of the metal complex. Our laboratory has pioneered the preparation and study of these complexes. In particular, we have applied femtosecond pump-probe spectroscopy to reveal excited state details of the isomerization mechanism. The data from numerous complexes allowed us to predict that the isomerization was nonadiabatic in nature, defined as occurring from a S-bonded triplet excited state (primarily metal-to-ligand charge transfer in character) to an O-bonded singlet ground state potential energy surface. This prediction was corroborated by high-level density functional theory calculations. An intriguing aspect of this reactivity is the coupling of nuclear motion to the electronic wave function and how this coupling affects motions productive for isomerization. In an effort to learn more about this coupling, we designed a project to examine phototriggered isomerization in bis-sulfoxide complexes. The goal of these studies was to determine whether certain complexes could be designed in which a single photon excitation event would prompt two sulfoxide isomerizations. We employed chelating sulfoxides in this study and found that both the nature of the chelate ring and the R group on the sulfoxide affect the photochemical reactivity. For example, this reactivity may be tuned such that two sulfoxide ligands isomerize sequentially following two successive excitations or that two sulfoxide ligands isomerize following a single excitation. This Account explains our understanding to date of this photochemistry. PMID:25761274

King, Albert W; Wang, Lei; Rack, Jeffrey J

2015-04-21

307

Resonant excitation of plasma wakefield  

NASA Astrophysics Data System (ADS)

Particle accelerators are the main tool for discovering new elementary particles. Plasma based accelerator (PWFA) has been proven a very attractive new acceleration technique due to the large acceleration gradient it has reached (>50GV/m), which is two to three orders higher than the conventional radio frequency accelerators. PWFA is essentially an energy transformer transferring the energy from the drive bunches to witness bunches. For a future more compact and more affordable linear electron/positron collider, such an accelerator will require drive bunches with small longitudinal size (on the order of 100 um) and multi-kilojules of energy to access the new physics at the energy frontier. However, present relativistic electron bunch drivers carry less than 100Joules, thereby limiting the energy gain by the accelerated bunch to less than 100Joules. Proton bunches produced at CERN have been proven as potential drivers for PWFA due to the many tens of kilojules energy they carry (1e11 particles, 3.5-7TeV per particle). However, the CERN proton bunches are too long (approximately 12cm) to drive the wakefield efficiently. It has been proposed that a long particle bunch (protons, electrons, positrons, ... ) traveling in dense plasmas is subject to self-modulation instability (SMI), which transversely modulates a long bunch into multiple short bunches (on the scale of plasma wavelength) and therefore results in high acceleration amplitudes through resonant excitation. In this thesis, we demonstrate the first experimental evidence for the seeding of SMI with an electron bunch. We also use numerical simulations to study the SMI development with a higher-charge electron bunch and propose a possible experiment to demonstrate the transverse modulation directly in experiments. Moreover, we investigate with simulations the effect of transverse plasma radius on the SMI development, which is an important factor to consider when designing plasmas for future SMI and SMI-based experiments. Besides efficient drivers such as high-energy proton bunches, the PWFA also requires high transformer ratio (an indication of energy transfer efficiency) so that the witness bunch can gain energy efficiently from the drive bunch. In this thesis, we explore the possibility of reaching high transformer ratio in the weakly nonlinear PWFA regime so that the witness bunch particles can gain many times the energy of the drive bunch particles in a single acceleration stage.

Fang, Yun

308

A theoretical study of the excited states of Ag3  

NASA Technical Reports Server (NTRS)

Calculations of the excited states of the Ag3 molecule are reported. The excitation energies, geometries, derived harmonic frequencies, and transition moments are given and discussed. The results of other calculations of the excited states are reviewed and assessed.

Walch, Stephen P.

1987-01-01

309

Wine Science Wine Sciencee Science  

E-print Network

Wine Science Wine Sciencee Science Thomas Henick-Kling Professor of Enology Director of Viticulture & Enology Program #12;Wine Science Wine Science Growth of Washington Wine Industry #12;Wine Science Wine Science Wine Grapes utilized 2007 2008 2009 2010 WA 127,000 145,000 156,000 160,000 NY 24,000 26,000 30

310

Students Excited by Stellar Discovery  

NASA Astrophysics Data System (ADS)

In the constellation of Ophiuchus, above the disk of our Milky Way Galaxy, there lurks a stellar corpse spinning 30 times per second -- an exotic star known as a radio pulsar. This object was unknown until it was discovered last week by three high school students. These students are part of the Pulsar Search Collaboratory (PSC) project, run by the National Radio Astronomy Observatory (NRAO) in Green Bank, WV, and West Virginia University (WVU). The pulsar, which may be a rare kind of neutron star called a recycled pulsar, was discovered independently by Virginia students Alexander Snider and Casey Thompson, on January 20, and a day later by Kentucky student Hannah Mabry. "Every day, I told myself, 'I have to find a pulsar. I better find a pulsar before this class ends,'" said Mabry. When she actually made the discovery, she could barely contain her excitement. "I started screaming and jumping up and down." Thompson was similarly expressive. "After three years of searching, I hadn't found a single thing," he said, "but when I did, I threw my hands up in the air and said, 'Yes!'." Snider said, "It actually feels really neat to be the first person to ever see something like that. It's an uplifting feeling." As part of the PSC, the students analyze real data from NRAO's Robert C. Byrd Green Bank Telescope (GBT) to find pulsars. The students' teachers -- Debra Edwards of Sherando High School, Leah Lorton of James River High School, and Jennifer Carter of Rowan County Senior High School -- all introduced the PSC in their classes, and interested students formed teams to continue the work. Even before the discovery, Mabry simply enjoyed the search. "It just feels like you're actually doing something," she said. "It's a good feeling." Once the pulsar candidate was reported to NRAO, Project Director Rachel Rosen took a look and agreed with the young scientists. A followup observing session was scheduled on the GBT. Snider and Mabry traveled to West Virginia to assist in the follow-up observations, and Thompson joined online. "Observing with the students is very exciting. It gives the students a chance to learn about radio telescopes and pulsar observing in a very hands-on way, and it is extra fun when we find a pulsar," said Rosen. Snider, on the other hand, said, "I got very, very nervous. I expected when I went there that I would just be watching other people do things, and then I actually go to sit down at the controls. I definitely didn't want to mess something up." Everything went well, and the observations confirmed that the students had found an exotic pulsar. "I learned more in the two hours in the control room than I would have in school the whole day," Mabry said. Pulsars are spinning neutron stars that sling lighthouse beams of radio waves or light around as they spin. A neutron star is what is left after a massive star explodes at the end of its normal life. With no nuclear fuel left to produce energy to offset the stellar remnant's weight, its material is compressed to extreme densities. The pressure squeezes together most of its protons and electrons to form neutrons; hence, the name neutron star. One tablespoon of material from a pulsar would weigh 10 million tons -- as much as a supertanker. The object that the students discovered is in a special class of pulsar that spins very fast - in this case, about 30 times per second, comparable to the speed of a kitchen blender. "The big question we need to answer first is whether this is a young pulsar or a recycled pulsar," said Maura McLaughlin, an astronomer at WVU. "A pulsar spinning that fast is very interesting as it could be newly born or it could be a very old, recycled pulsar." A recycled pulsar is one that was once in a binary system. Material from the companion star is deposited onto the pulsar, causing it to speed up, or be recycled. Mystery remains, however, about whether this pulsar has ever had a companion star. If it did, "it may be t

2011-02-01

311

Acoustics of Excited Jets: A Historical Perspective  

NASA Technical Reports Server (NTRS)

The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

Brown, Cliffard A.

2005-01-01

312

The DSS-14 C-band exciter  

NASA Technical Reports Server (NTRS)

The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

Rowan, D. R.

1989-01-01

313

Magnetic Excitation for Spin Vibration Testing  

NASA Technical Reports Server (NTRS)

The Dynamic Spin Rig Laboratory (DSRL) at the NASA Lewis Research Center is a facility used for vibration testing of structures under spinning conditions. The current actuators used for excitation are electromagnetic shakers which are configured to apply torque to the rig's vertical rotor. The rotor is supported radially and axially by conventional bearings. Current operation is limited in rotational speed, excitation capability, and test duration. In an effort to enhance its capabilities, the rig has been initially equipped with a radial magnetic bearing which provides complementary excitation and shaft support. The new magnetic feature has been used in actual blade vibration tests and its performance has been favorable. Due to the success of this initial modification further enhancements are planned which include making the system fully magnetically supported. This paper reports on this comprehensive effort to upgrade the DSRL with an emphasis on the new magnetic excitation capability.

Johnson, Dexter; Mehmed, Oral; Brown, Gerald V.

1997-01-01

314

Detecting cracked rotors using auxiliary harmonic excitation  

NASA Astrophysics Data System (ADS)

Cracked rotors are not only important from a practical and economic viewpoint, they also exhibit interesting dynamics. This paper investigates the modelling and analysis of machines with breathing cracks, which open and close due to the self-weight of the rotor, producing a parametric excitation. After reviewing the modelling of cracked rotors, the paper analyses the use of auxiliary excitation of the shaft, often implemented using active magnetic bearings to detect cracks. Applying a sinusoidal excitation generates response frequencies that are combinations of the rotor spin speed and excitation frequency. Previously this system was analysed using multiple scales analysis; this paper suggests an alternative approach based on the harmonic balance method, and validates this approach using simulated and experimental results. Consideration is also given to some issues to enable this approach to become a robust condition monitoring technique for cracked shafts.

Sawicki, Jerzy T.; Friswell, Michael I.; Kulesza, Zbigniew; Wroblewski, Adam; Lekki, John D.

2011-03-01

315

Stimulated excitation electron microscopy and spectroscopy.  

PubMed

Recent advances in instrumentation for electron optics and spectroscopy have prompted exploration of ultra-low excitations such as phonons, bond vibrations and Johnson noise. These can be excited not just with fast electrons but also thermally or by other external sources of radiation. The near-field theory of electron energy loss and gain provides a convenient platform for analysing these processes. Possibilities for selected phonon mapping and imaging are discussed. Effects should certainly be observable in atomic resolution structure imaging but diffraction contrast imaging could perhaps be more informative. Additional exciting prospects to be explored include the transition from phonon excitation to single atom recoil and the boosting of energy loss and gain signals with tuned laser illumination. PMID:25312246

Howie, A

2015-04-01

316

On Oscillators in Phyllosilicate Excitable Automata  

NASA Astrophysics Data System (ADS)

Phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate excitable automaton is a regular network of finite state machines, which mimics structure of a silicate sheet. A node of the silicate sheet is an automaton, which takes resting, excited and refractory states, and updates its state in discrete time depending on a sum of excited states of its three (silicon automata) or six (oxygen automata) closest neighbors. Oscillator is a localized compact configuration of nonquiescent states which undergoes finite growth and modification but returns to its original state in a finite number of steps. We show that phyllosilicate excitable automata exhibit waves and oscillating localizations (oscillators) dynamics. Basic types of oscillators are classified and characterized.

Adamatzky, Andrew

2013-06-01

317

Excitation with Effective Subcycle Laser Pulses  

NASA Astrophysics Data System (ADS)

We have used laser pulses with a temporally shaped polarization to demonstrate the multiphoton excitation of the xenon 5g state within a subcycle of a laser pulse. Our polarization gated laser pulses are composed of circularly polarized sections at the leading and trailing edges of the pulse and of an experimentally defined linearly polarized central part. Only the linear part (the gate) of the pulse can excite neutral xenon in the 5g state. The transition cannot be driven with circularly polarized light because the number of photons needed would cause a violation of selection rules for the change of the magnetic quantum number. We show that the linearly polarized central part can be reduced to a subcycle pulse. This allows us to study excitation with an effective pulse as short as 2.3 fs at 800 nm. Electron imaging spectroscopy has been used to visualize the presence of excited states as a function of the pulse duration of the gate.

Marceau, C.; Gingras, G.; Witzel, B.

2013-11-01

318

46 CFR 111.12-3 - Excitation.  

Code of Federal Regulations, 2011 CFR

...SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits 111.12-3...may be used for excitation of an emergency generator unless it is provided with a permanent...

2011-10-01

319

Bound excited states in 27F  

NASA Astrophysics Data System (ADS)

The 1H(27F, 25,26,27F) reactions have been studied at 40 MeV /nucleon average energy using a liquid hydrogen target. For 25F, 26F and 27F nuclei, we have observed two ?-ray peaks each originating from the decay of two bound excited states. This is the first sign of the existence of bound excited states in 26,27F. The presence of a single bound excited state in 27F is a clear indication of a substantial change in the structure of the fluorine isotopes approaching the neutron dripline. The proposed second excited states in 25,26,27F nuclei have no counterparts in either the psd or the sdpf shell model calculations suggesting the appearance of nuclear structure effects lying out of these model spaces.

Elekes, Z.; Dombrdi, Zs.; Saito, A.; Aoi, N.; Baba, H.; Demichi, K.; Flp, Zs.; Gibelin, J.; Gomi, T.; Hasegawa, H.; Imai, N.; Ishihara, M.; Iwasaki, H.; Kanno, S.; Kawai, S.; Kishida, T.; Kubo, T.; Kurita, K.; Matsuyama, Y.; Michimasa, S.; Minemura, T.; Motobayashi, T.; Notani, M.; Ohnishi, T.; Ong, H. J.; Ota, S.; Ozawa, A.; Sakai, H. K.; Sakurai, H.; Shimoura, S.; Takeshita, E.; Takeuchi, S.; Tamaki, M.; Togano, Y.; Yamada, K.; Yanagisawa, Y.; Yoneda, K.

2004-10-01

320

Bound excited states in 27F  

NASA Astrophysics Data System (ADS)

The 1H(27F,25,26,27F) reactions have been studied at 40 MeV/nucleon average energy using a liquid hydrogen target. For 25F, 26F and 27F nuclei, we have observed two ?-ray peaks each originating from the decay of two bound excited states. This is the first sign of the existence of bound excited states in 26,27F. The presence of a single bound excited state in 27F is a clear indication of a substantial change in the structure of the fluorine isotopes approaching the neutron dripline. The proposed second excited states in 25,26,27F nuclei have no counterparts in either the psd or the sdpf shell model calculations suggesting the appearance of nucler structure effects lying out of these model spaces.

Elekes, Z.; Dombrdi, Zs.; Saito, A.; Aoi, N.; Baba, H.; Demichi, K.; Flp, Zs.; Gibelin, J.; Gomi, T.; Hasegawa, H.; Imai, N.; Ishihara, M.; Iwasaki, H.; Kanno, S.; Kawai, S.; Kishida, T.; Kubo, T.; Kurita, K.; Matsuyama, Y.; Michimasa, S.; Minemura, T.; Motobayashi, T.; Notani, M.; Ohnishi, T. K.; Ong, H. J.; Ota, S.; Ozawa, A.; Sakai, H. K.; Sakurai, H.; Shimoura, S.; Takeshita, E.; Takeuchi, S.; Tamaki, M.; Togano, Y.; Yamada, K.; Yanagisawa, Y.; Yoneda, K.

2006-03-01

321

Setting the Scene: Basic Rules for a Safer Science Classroom  

NSDL National Science Digital Library

Six classes, six teachers--just navigating middle school is a voyage of discovery for early adolescents. We offer them a confusing array of choices, many in science. Sometimes it seems we spend too much science class time teaching organization, caution, and control. But these skills--critical to making science experiences exciting and safe--are also important science processes. This free selection includes the Table of Contents, Foreword, Introduction, and References.

Juliana Texley

2003-01-01

322

Self excitation of iron core homopolar generators  

Microsoft Academic Search

In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at the University of Texas. In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A

D. E. Perkins; K. E. Nalty; W. A. Walls

1986-01-01

323

Fast pulsed excitation wiggler or undulator  

DOEpatents

A fast pulsed excitation, electromagnetic undulator or wiggler, employing geometrically alternating substacks of thin laminations of ferromagnetic material, together with a single turn current loop excitation of the composite assembly, of such shape and configuration that intense, spatially alternating, magnetic fields are generated; for use as a pulsed mode undulator or wiggler radiator, for use in a Free Electron Laser (FEL) type radiation source or, for use in an Inverse Free Electron Laser (IFEL) charged particle accelerator.

van Steenbergen, Arie (Shoreham, NY)

1990-01-01

324

Molecular rotovibrational dynamics excited in optical filamentation.  

PubMed

The rotovibrational dynamics excited by optical filamentation in molecular gases is studied in the temporal domain. Two time-delayed replicas of the same laser pulse have been used to generate a first filament, for the rotovibrational excitation of the sample, and a second collinear filament probing the Raman dynamics. The Fermi doublet structure in CO(2) as well as the very fast stretching mode of H(2) were clearly resolved. PMID:19079493

Calegari, F; Vozzi, C; De Silvestri, S; Stagira, S

2008-12-15

325

Evolution of locally excited avalanches in semiconductors  

E-print Network

We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \\textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

2010-05-25

326

Try Science  

NSDL National Science Digital Library

TryScience contains games and virtual reality adventures, virtual field trips to museums and science centers, and experiments. There is a Starfleet Academy virtual reality game involving communications, engineering, environments, and lifeforms; an electrolysis experiment that can be conducted online or at home; and a game about an African Naked Mole-rat colony. Experiments are categorized by: Earth science, biological science, mathematics, physical science, space science, technology and engineering, chemistry, social science, and medicine and health.

327

Antecedents of two-photon excitation laser scanning microscopy.  

PubMed

In 1931, Maria Gppert-Mayer published her doctoral dissertation on the theory of two-photon quantum transitions (two-photon absorption and emission) in atoms. This report describes and analyzes the theoretical and experimental work on nonlinear optics, in particular two-photon excitation processes, that occurred between 1931 and the experimental implementation of two-photon excitation microscopy by the group of Webb in 1990. In addition to Maria Gppert-Mayer's theoretical work, the invention of the laser has a key role in the development of two-photon microscopy. Nonlinear effects were previously observed in different frequency domains (low-frequency electric and magnetic fields and magnetization), but the high electric field strength afforded by lasers was necessary to demonstrate many nonlinear effects in the optical frequency range. In 1978, the first high-resolution nonlinear microscope with depth resolution was described by the Oxford group. Sheppard and Kompfner published a study in Applied Optics describing microscopic imaging based on second-harmonic generation. In their report, they further proposed that other nonlinear optical effects, such as two-photon fluorescence, could also be applied. However, the developments in the field of nonlinear optical stalled due to a lack of a suitable laser source. This obstacle was removed with the advent of femtosecond lasers in the 1980s. In 1990, the seminal study of Denk, Strickler, and Webb on two-photon laser scanning fluorescence microscopy was published in Science. Their paper clearly demonstrated the capability of two-photon excitation microscopy for biology, and it served to convince a wide audience of scientists of the potential capability of the technique. PMID:14677127

Masters, Barry R; So, Peter T C

2004-01-01

328

Calculation of He photoionization with excitation and de-excitation cross section  

Microsoft Academic Search

We present calculation results for photo-ionization with de- excitation of excited He and helium-like ions at high but non- relativistic photon energies phi. The cross-section of this process is expressed in fact via integrals similar to that used already in description of two-electron ionization and ionization with excitation. In principle, the considered process can be separated pure experimentally from other

Miron Ya. Amusia; Rajmund Krivec

2005-01-01

329

Frster excitation energy transfer in peridinin-chlorophyll-a-protein.  

PubMed Central

Time-resolved fluorescence anisotropy spectroscopy has been used to study the chlorophyll a (Chl a) to Chl a excitation energy transfer in the water-soluble peridinin-chlorophyll a-protein (PCP) of the dinoflagellate Amphidinium carterae. Monomeric PCP binds eight peridinins and two Chl a. The trimeric structure of PCP, resolved at 2 A (, Science. 272:1788-1791), allows accurate calculations of energy transfer times by use of the Frster equation. The anisotropy decay time constants of 6.8 +/- 0.8 ps (tau(1)) and 350 +/- 15 ps (tau(2)) are respectively assigned to intra- and intermonomeric excitation equilibration times. Using the ratio tau(1)/tau(2) and the amplitude of the anisotropy, the best fit of the experimental data is achieved when the Q(y) transition dipole moment is rotated by 2-7 degrees with respect to the y axis in the plane of the Chl a molecule. In contrast to the conclusion of, Biochemistry. 23:1564-1571) that the refractive index (n) in the Frster equation should be equal to that of the solvent, n can be estimated to be 1.6 +/- 0.1, which is larger than that of the solvent (water). Based on our observations we predict that the relatively slow intermonomeric energy transfer in vivo is overruled by faster energy transfer from a PCP monomer to, e.g., the light-harvesting a/c complex. PMID:10620298

Kleima, F J; Hofmann, E; Gobets, B; van Stokkum, I H; van Grondelle, R; Diederichs, K; van Amerongen, H

2000-01-01

330

Analysis of the Z(4430) as the First Radial Excitation of the Zc(3900)  

NASA Astrophysics Data System (ADS)

In this article, we take the Zc(3900) and Z(4430) as the ground state and the first radial excited state of the axial-vector tetraquark states with JPC = 1+?, respectively, and study their masses and pole residues with the QCD sum rules by calculating the contributions of the vacuum condensates up to dimension-10 in a consistent way in the operator product expansion. The numerical result favors assigning the Zc(3900) and Z(4430) as the ground state and first radial excited state of the axial-vector tetraquark states, respectively. Supported by National Natural Science Foundation under Grant No. 11375063, and Natural Science Foundation of Hebei Province under Grant No. A2014502017

Wang, Zhi-Gang

2015-03-01

331

Editor's Corner: Small Science  

NSDL National Science Digital Library

We know that nanotechnology offers real possibilities. It already appears in commercial products such as computers, sunscreens, high-performance sporting equipment, and stain-resistant fabrics. The evolution from vacuum tubes to transistors and high-density integrated circuits has transformed the modern world. Nature itself has shown the way to nanoscale engineering, with molecule-sized assembly lines such as ribosomes and DNA polymerase. Clearly, this "small science" has huge possibilities! The Field Editor discusses the exciting world of nanotechnology in this month's Editor's Corner column.

2006-12-01

332

Science Experiments at Home  

NSDL National Science Digital Library

Professor Bassam Z. Shakhashiri, at the University of Wisconsin - Madison, offers many fun, easy chemistry experiments at this website. Through the utilization of a few household materials, users can learn about pressure, acids and bases, chemiluminescent chemical reactions, and more. The activities are filled with thought provoking questions along with concise explanations about the topic presented. The website provides links to activities dealing with topics in physics as well. Anyone interested in partaking in simple, yet exciting, science experiments with their family and friends at home should visit this website.

2007-12-12

333

Computer Science  

NSDL National Science Digital Library

Computer science is the study of computational systems and their use in representing important problems in science and society. Major topics include computational science, software systems, network systems, theory of computation, machine learning, and human-computer interaction.

K-12 Outreach,

334

Cherenkov-excited luminescence scanned imaging.  

PubMed

Ionizing radiation is commonly delivered by medical linear accelerators (LINAC) in the form of shaped beams, and it is able to induce Cherenkov emission in tissue. In fluorescence-based microscopy excitation from scanned spots, lines, or sheets can be used for fast high-resolution imaging. Here we introduce Cherenkov-excited luminescence scanned imaging (CELSI) as a new imaging methodology utilizing 2-dimensional (?5-mm-thick) sheets of LINAC radiation to produce Cherenkov photons, which in turn excite luminescence of probes distributed in biological tissues. Imaging experiments were performed by scanning these excitation sheets in three orthogonal directions while recording Cherenkov-excited luminescence. Tissue phantom studies have shown that single luminescent inclusions ?1??mm in diameter can be imaged within 20-mm-thick tissue-like media with minimal loss of spatial resolution. Using a phosphorescent probe for oxygen, PtG4 with the CELSI methodology, an image of partial pressure of oxygen (pO2) was imaged in a rat lymph node, quantitatively restoring pO2 values in differently oxygenated tissues. PMID:25723443

Zhang, Rongxiao; D'souza, Alisha V; Gunn, Jason R; Esipova, Tatiana V; Vinogradov, Sergei A; Glaser, Adam K; Jarvis, Lesley A; Gladstone, David J; Pogue, Brian W

2015-03-01

335

Atmospheric Excitation of Planetary Normal Modes  

NASA Technical Reports Server (NTRS)

The objectives of this study were to: (1) understand the phenomenon of continuous free oscillations of the Earth and (2) examine the idea of using this phenomenon for planetary seismology. We first describe the results on (1) and present our evaluations of the idea (2) in the final section. In 1997, after almost forty years since the initial attempt by Benioff et al, continuous free oscillations of the Earth were discovered. Spheroidal fundamental modes between 2 and 7 millihertz are excited continuously with acceleration amplitudes of about 0.3-0.5 nanogals. The signal is now commonly found in virtually all data recorded by STS-1 type broadband seismometers at quiet sites. Seasonal variation in amplitude and the existence of two coupled modes between the atmosphere and the solid Earth support that these oscillations are excited by the atmosphere. Stochastic excitation due to atmospheric turbulence is a favored mechanism, providing a good match between theory and data. The atmosphere has ample energy to support this theory because excitation of these modes require only 500-10000 W whereas the atmosphere contains about 117 W of kinetic energy. An application of this phenomenon includes planetary seismology, because other planets may be oscillating due to atmospheric excitation. The interior structure of planets could be learned by determining the eigenfrequencies in the continuous free oscillations. It is especially attractive to pursue this idea for tectonically quiet planets, since quakes may be too infrequent to be recorded by seismic instruments.

Tanimoto, Toshiro

2001-01-01

336

1 Forensic Sciences FORENSIC SCIENCES  

E-print Network

1 Forensic Sciences FORENSIC SCIENCES As part of the Columbian College of Arts and Sciences' natural, mathematical and biomedical sciences programs, the forensic sciences program provides an understanding of the integration of forensic disciplines with the investigation of criminal activity, along

Vertes, Akos

337

1 Political Science POLITICAL SCIENCE  

E-print Network

1 Political Science POLITICAL SCIENCE With Capitol Hill nearby and the White House just blocks away, GW is the ideal place to study political science. Students in the program benefit from rigorous study and behavioral sciences discipline in the Columbian College of Arts and Sciences, the program examines politics

Vertes, Akos

338

Earth Sciences Environmental Earth Sciences,  

E-print Network

94 Earth Sciences­ Environmental Earth Sciences, Geology Degree options MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint placement. * The Geology and Environmental Earth Sciences degrees are accredited by the Geological Society

Brierley, Andrew

339

Designing a Mars Mission that Will Generate Public Excitement and Support: Sample Return Using In Situ Propellant Production  

Microsoft Academic Search

Publicly funded space missions (e.g. all NASA missions) must be perceived by the public as worthwhile in order to retain broad support for NASA and a sustainable space program. In addition, if the public finds the missions exciting and even entertaining, then the level of support will be even greater. 'Good Science' alone is not enough to keep the public

P. J. Mueller

2000-01-01

340

Dear Camper Parent, The 2014 Physics Summer Camp is approaching and we are excited at the prospect of sharing  

E-print Network

Dear Camper Parent, The 2014 Physics Summer Camp is approaching and we are excited at the prospect on this year's Science Summer Camp and registration forms. Please look over the contents of this packet with payment as soon as possible. (Enrollment can also be completed online at http://physics.maine.edu/summer-camp

Thomas, Andrew

341

Patterns of conductivity in excitable automata with updatable intervals of excitations.  

PubMed

We define a cellular automaton where a resting cell excites if number of its excited neighbors belong to some specified interval and boundaries of the interval change depending on ratio of excited and refractory neighbors in the cell's neighborhood. We calculate excitability of a cell as a number of possible neighborhood configurations that excite the resting cell. We call cells with maximal values of excitability conductive. In exhaustive search of functions of excitation interval updates we select functions which lead to formation of connected configurations of conductive cells. The functions discovered are used to design conductive, wirelike, pathways in initially nonconductive arrays of cells. We demonstrate that by positioning seeds of growing conductive pathways it is possible to implement a wide range of routing operations, including reflection of wires, stopping wires, formation of conductive bridges, and generation of new wires in the result of collision. The findings presented may be applied in designing conductive circuits in excitable nonlinear media, reaction-diffusion chemical systems, neural tissue, and assemblies of conductive polymers. PMID:23214841

Adamatzky, Andrew

2012-11-01

342

Patterns of conductivity in excitable automata with updatable intervals of excitations  

NASA Astrophysics Data System (ADS)

We define a cellular automaton where a resting cell excites if number of its excited neighbors belong to some specified interval and boundaries of the interval change depending on ratio of excited and refractory neighbors in the cell's neighborhood. We calculate excitability of a cell as a number of possible neighborhood configurations that excite the resting cell. We call cells with maximal values of excitability conductive. In exhaustive search of functions of excitation interval updates we select functions which lead to formation of connected configurations of conductive cells. The functions discovered are used to design conductive, wirelike, pathways in initially nonconductive arrays of cells. We demonstrate that by positioning seeds of growing conductive pathways it is possible to implement a wide range of routing operations, including reflection of wires, stopping wires, formation of conductive bridges, and generation of new wires in the result of collision. The findings presented may be applied in designing conductive circuits in excitable nonlinear media, reaction-diffusion chemical systems, neural tissue, and assemblies of conductive polymers.

Adamatzky, Andrew

2012-11-01

343

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media  

E-print Network

NL3451 Vortex dynamics in excitable media 1 NL3451 Vortex dynamics in excitable media Statics the form u = U(r, t) = U((r), (r) + t) P((r) - 2 ((r) + t)) + , (2) where (r) and (r) are the polar. Typically, a spiral wave in a given system develops the same kind of meander #12;NL3451 Vortex dynamics

Biktashev, Vadim N.

344

Evaluation of the Long-Term Impact of a University High School Summer Science Program on Students' Interest and Perceived Abilities in Science  

ERIC Educational Resources Information Center

Many biomedical research universities have established outreach programs for precollege students and teachers and partnerships with local school districts to help meet the challenges of science education reform. Science outreach programs held in university research facilities can make science more exciting and innovative for high school students

Markowitz, Dina G.

2004-01-01

345

Influence of excitation and deexcitation processes on the dynamics of laser-excited argon clusters  

NASA Astrophysics Data System (ADS)

The excitation of atomic clusters by intense infrared laser pulses leads to the creation of highly charged ions and to the emission of energetic photons. These phenomena, which follow from ionization processes occurring in the cluster, depend significantly on the population of ground states and excited states in the laser-produced nanoplasma. This makes it necessary to account for collisional excitation and deexcitation processes. We investigate the interaction of femtosecond laser pulses with argon clusters by means of a nanoplasma model. Considering laser excitation with single and double pulses, we analyze the role of excitation and deexcitation processes in detail and calculate the yield of highly charged ions and of energetic photons in different wavelength regimes.

Moll, M.; Schlanges, M.; Bornath, Th.; Krainov, V. P.

2015-03-01

346

Self excitation of iron core homopolar generators  

NASA Astrophysics Data System (ADS)

In the interest of reducing homopolar generator (HPG) auxiliary requirements, a self-excited field coil for pulsed duty, iron-core HPG has been developed and tested at the Center for Electromechanics at the University of Texas. In order to minimize rotor energy expended during excitation, a low-resistance, low-inductance coil was desired to allow field current to rise as rapidly as possible. A seven-turn field coil, having a nominal resistance of 500 micro-ohms was fabricated for the compact HPG system tester and subsequently tested. At 6,000 rpm, a field current rise time of 1 sec was achieved and resulted in an average peak field density of 1.94 T. Only 300 kJ, about 13 percent of the 2.27 MJ stored in the rotor was required to fully excite the generator.

Perkins, D. E.; Nalty, K. E.; Walls, W. A.

1986-11-01

347

Excitation of a composite structure by collisions  

NASA Astrophysics Data System (ADS)

A simple model is employed to study the excitation of a composite structure by collisions. The composite structure is a diatomic ``molecule'' composed of two equal point masses joined by a Hooke's law spring of constant, k1. This structure, in an unexcited state, makes a one-dimensional head-on collision with a fixed wall. The interaction with the wall is mediated by a second Hooke's law spring of constant, k2. After rebounding from the wall the diatom may be in an excited state. The excitation energy is calculated as a function of the hardness of the wall. An eigenvalue problem is solved which yields an infinite number of ?'s (?=k1/k2) which leave the diatom unexcited. The phenomenon of ``double hitting'' when a soft structure strikes a hard wallis discussed. The maximum energy transfer into the internal mode is 23%. An air-track experiment is suggested to check the theoretical predictions.

Newby, Neal D.

1984-08-01

348

NMR solvent peak suppression by nonlinear excitation  

NASA Astrophysics Data System (ADS)

Most existing NMR solvent peak suppression sequences provide a satisfactory dependence of the intensity of excited signals on frequency but poor phase characteristics. In practice this leads to spectral distortions which generally become more severe as the frequency selectivity of the sequence is increased. However, it is shown that by working well outside the linear response regime, excitation schemes which combine high frequency selectivity with good phase properties may be devised. Sequences of six rectangular radio-frequency pulses were discovered using a combination of coherent averaging theory to treat the near-resonant behavior and numerical simulation further from resonance. Extensive use of symmetry greatly simplifies both the coherent averaging calculations and the numerical simulations. The new pulse sequences have been given the acronym NERO (nonlinear excitation rejecting on-resonance). Experimental spectra of an enzyme in dilute aqueous solution are shown.

Levitt, Malcolm H.

1988-03-01

349

Charge-displacement analysis for excited states  

SciTech Connect

We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

Ronca, Enrico, E-mail: enrico@thch.unipg.it; Tarantelli, Francesco, E-mail: francesco.tarantelli@unipg.it [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy) [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Dipartimento di Chimica, Biologia e Biotecnologie, Universit degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia (Italy); Pastore, Mariachiara, E-mail: chiara@thch.unipg.it; Belpassi, Leonardo; De Angelis, Filippo [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy)] [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Angeli, Celestino; Cimiraglia, Renzo [Dipartimento di Scienze Chimiche e Farmaceutiche, Universit degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)] [Dipartimento di Scienze Chimiche e Farmaceutiche, Universit degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)

2014-02-07

350

Electronic excitation transport, diffusion and trapping  

NASA Astrophysics Data System (ADS)

Excitation energy transfer between donor (trypaflavine) and acceptor (rhodamine B, rhodamine 6G and cresyl violet) molecules randomly distributed in condensed phases is investigated using a time correlated single photon counting technique. The influence of excitation migration and translational diffusion is experimentally observed. The donor decay data demonstrate that fast diffusion/migration governs the decay kinetics in low viscosity solutions the donor fluorescence decay being single exponential. The value of the diffusion coefficient calculated from decay curve analysis is almost a factor of five larger than the spatial diffusion constant and two orders of magnitude faster than the excitation migration transport constant. In high viscosity solvents efficient energy transfer follows the Frster dipoledipole model.

Pandey, K. K.

1992-09-01

351

Excited states in electronic structure calculations  

SciTech Connect

A first-principles quasiparticle approach to the electronic excitation energies in crystals and at surfaces is described. The quasiparticle energies are calculated within the GW approximation for comparison with photoemission and other spectroscopic experiments. Applications of the method to bulk semiconductors and the Si(111)2[times]l, Ge(111)2[times]l. and H/Si(III) surfaces are presented. In both cases, significant self-energy corrections arising from many-electron effects to the excitation energies are found. Using atomic positions from total energy minimization, the calculated excitation energies explain quantitatively the experimental spectra. This approach thus provides an ab initio means for analyzing and predicting results from spectroscopic probes.

Louie, S.G.

1992-07-01

352

Two photon excited fluorescence from diamond nanoparticles  

NASA Astrophysics Data System (ADS)

The possibility of two photon eaxcited fluorescence by diamond nanoparticles is an interesting nonlinear phenomenon. We have grown 20-100 nm diamond nanoparticles by using chemical vapor deposition (CVD) and characterized their properties by using complementary techniques of AFM, SEM, and Raman spectroscopy.footnotetextR. Chakraborty, S. C. Sharma, and J. K. LaRoque, J. Nano Research, 12, 1123 (2010)^,footnotetextR. Chakraborty and S. C. Sharma, Physica B, 406, 4170 (2011) In this work, we have utilized femtosecond laser based two-photon excitation to study the emission of visible light ( 530 nm) as functions of the excitation wavelength (750-850 nm), excitation power, and size of the NPs. These results and their potential applications will be discussed.

Singh, Ankit; Ajaeroh, Mathias; Mohanty, Samar; Sharma, Suresh

2012-10-01

353

Triplet excitations in graphene-based systems  

NASA Astrophysics Data System (ADS)

In this paper we investigate the excitations in a single graphene layer and in a single-walled carbon nanotube, i.e. the spectrum of magnetic excitations is calculated. In the absence of interactions in these systems there is a unique gap in the electron-hole continuum. We show that in the presence of Coulomb correlations bound states, magnons, appear in this forbidden region. The Coulomb interaction is examined in the context of the Pariser-Parr-Pople (PPP) model which takes into account the long-range nature of the interaction. The energy of the new bound states depends on the strength of the Coulomb forces. The calculations are performed for arbitrary electron-hole (e\\text-h) momentum q . In the end, this work finally settles the discussion sabout the existence of triplet excitations in graphene which has been lasting for a decade in the literature.

Posvyanskiy, V.; Arnarson, L.; Hedegrd, P.

2015-02-01

354

Excited light meson spectroscopy from lattice QCD  

SciTech Connect

I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.

Christopher Thomas, Hadron Spectrum Collaboration

2012-04-01

355

Parametric array technique for microbubble excitation.  

PubMed

This study investigates the use of an acoustic parametric array as a means for microbubble excitation. The excitation wave is generated during propagation in a nonlinear medium of two high-frequency carrier waves, whereby the frequency of the excitation wave is the difference frequency of the carrier waves. Carrier waves of around 10 and 25 MHz are used to generate low-frequency waves between 0.5 and 3.5 MHz at amplitudes in the range of 25 to 80 kPa in water. We demonstrate with high-speed camera observations that it is possible to induce microbubble oscillations with the low frequency signal arising from the nonlinear propagation process. As an application, we determined the resonance frequency of Definity contrast agent microbubbles with radius ranging from 1.5 to 5 ?m by sweeping the difference frequency in the range from 0.5 to 3.5 MHz. PMID:21622048

Vos, Hendrik J; Goertz, David E; van der Steen, Antonius F W; de Jong, Nico

2011-05-01

356

Testing the excitability of human motoneurons  

PubMed Central

The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483

McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.

2013-01-01

357

Shear layer excitation, experiment versus theory  

NASA Technical Reports Server (NTRS)

The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

Bechert, D. W.; Stahl, B.

1984-01-01

358

Excitation of gravity waves in common envelopes  

NASA Technical Reports Server (NTRS)

We study the excitation of gravity waves by a low-mass companion orbiting inside the envelope of a giant star, concentrating on brown dwarfs inside the envelope of asymptotic giant branch stars. Efficient g-wave excitations occur only after the brown dwarf has spiraled-in to the radiative zone, well inside the envelope, of the asymptotic giant branch star. The brown dwarf excites g-waves when its orbital radius is about 3-10 solar radii. At this stage of the evolution the envelope mass is below 0.1 solar mass. The g-waves propagate inward from the secondary orbit, carrying angular momentum and energy. We find that the angular momentum transport leads to an efficient spin-up of the inner envelopes. The differential rotation between the envelope and core and nonlinear wave effects, can cause a mixing of heavy elements from the core to the envelope.

Soker, Noam

1992-01-01

359

Crop Science Investigation (CSI) Network  

NSDL National Science Digital Library

Crop Science Investigation (CSI) Network This site is designed to serve as a clearinghouse of lesson plans and other materials useful for teaching 4-H and FFA youth about crop and soil sciences. Check out this site for information to use in your classroom, workshops, or 4-H meetings. As youth become less connected with agriculture, it is essential to teach them about agriculture. A series of workshops, called Crop Science Investigation or CSI was created to help spark the interest of youth to learn about crops and plants.Dig into some interesting facts about Nebraska crops.Learn how crops grow and factors that affect them.Learn about exciting career opportunities related to crop and plant science. The University of Nebraska offers great majors for anyone interested in anything plants! Check it out!

360

Lessons Learned from Conducting a K-12 Project to Revitalize Achievement by Using Instrumentation in Science Education  

ERIC Educational Resources Information Center

A student's first introduction to engineering and technology is typically through high school science labs. Unfortunately, in many high schools, science labs often make use of antiquated tools that fail to deliver exciting lab content. As a result, many students are turned off by science, fail to excel on standardized science exams, and do

Kapila, Vikram; Iskander, Magued

2014-01-01

361

CLSI: Cool Life Science Investigations  

NSDL National Science Digital Library

With the number of popular medical and forensics programs on television and many references in the media today, even elementary students can comfortably throw around terms such as cells, DNA, and artificial products. However, their questions on these topics often go unanswered, or they are left with misinformation regarding these concepts. As a result, a group of university science educators and the resource coordinator for an elementary school gifted program teemed up to create accurate, developmentally appropriate, and exciting experiences with these topics for students in grades K-5. The result of this collaborative effort was an after-school science "tradeshow," which is described here.

Carell Falsarella

2007-12-01

362

Communicating Science  

NASA Astrophysics Data System (ADS)

Introduction: what this book is about and why you might want to read it; Prologue: three orphans share a common paternity: professional science communication, popular journalism, and literary fiction are not as separate as they seem; Part I. Professional Science Communication: 1. Spreading the word: the endless struggle to publish professional science; 2. Walk like an Egyptian: the alien feeling of professional science writing; 3. The future's bright? Professional science communication in the age of the internet; 4. Counting the horse's teeth: professional standards in science's barter economy; 5. Separating the wheat from the chaff: peer review on trial; Part II. Science for the Public: What Science Do People Need and How Might They Get It?: 6. The Public Understanding of Science (PUS) movement and its problems; 7. Public engagement with science and technology (PEST): fine principle, difficult practice; 8. Citizen scientists? Democratic input into science policy; 9. Teaching and learning science in schools: implications for popular science communication; Part III. Popular Science Communication: The Press and Broadcasting: 10. What every scientist should know about mass media; 11. What every scientist should know about journalists; 12. The influence of new media; 13. How the media represents science; 14. How should science journalists behave?; Part IV. The Origins of Science in Cultural Context: Five Historic Dramas: 15. A terrible storm in Wittenberg: natural knowledge through sorcery and evil; 16. A terrible storm in the Mediterranean: controlling nature with white magic and religion; 17. Thieving magpies: the subtle art of false projecting; 18. Foolish virtuosi: natural philosophy emerges as a distinct discipline but many cannot take it seriously; 19. Is scientific knowledge 'true' or should it just be 'truthfully' deployed?; Part V. Science in Literature: 20. Science and the Gothic: the three big nineteenth-century monster stories; 21. Science fiction: serious literature of ideas or low-grade entertainment?; 22. Science in British literary fiction; 23. Science on stage: the politics and ethics of science in cultural and educational contexts.

Russell, Nicholas

2009-10-01

363

Picosecond x-ray science  

Microsoft Academic Search

The report discusses the exciting times for short pulse X-rays and the current users of the technology in the United States. Tracking nuclear motions with X-rays transcends scientific disciplines and includes Biology, Materials Science, Condensed Matter and Chemistry. 1 picosecond accesses many phenomena previously hidden at 100ps. Synchrotron advantage over laser plasma and LCLS is that it's easily tunable. There

E. Landahl; D. Reis; J. Wang; L. Young

2006-01-01

364

LMM Auger primary excitation spectra of copper  

NASA Astrophysics Data System (ADS)

The shape and intensity of measured Auger peaks are strongly affected by extrinsic excitations due to electron transport out of the surface and to intrinsic excitations induced by the sudden creation of the two static core holes. Following a method developed for XPS in a previous work [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17], we have calculated the effective energy-differential inelastic electron scattering cross-sections, including the effects of the surface and of the two core holes, within the dielectric response theory by means of the QUEELS-XPS software (QUantitative analysis of Electron Energy Losses at Surfaces for XPS). The Auger spectra are then modeled by convoluting this energy loss cross section with the primary excitation spectrum that accounts for all effects which are part of the initial Auger process, i.e. L-S coupling and vacancy satellite effects. The shape of this primary excitation spectrum is fitted to get close agreement between the theoretical and the experimental spectra obtained from X-ray excited Auger electron spectroscopy (XAES). We have performed these calculations of XAES spectra for various LMM Auger transitions of pure Cu (L3M45M45, L3M23M45, L3M23M23 and L2M45M45 transitions). We compare the resulting primary excitation spectra with theoretical results published in the literature and obtain reasonable quantitative agreement. In particular, we extract from experimental spectra quantitative intensities due to Coster-Kronig, shake-off and shake-up processes relative to the intensity from the normal Auger process.

Pauly, N.; Tougaard, S.; Yubero, F.

2014-12-01

365

Gluonic excitations in the hadronic spectrum  

SciTech Connect

QCD at low energy features a gluonic field that is strongly coupled to itself and to quarks. I will present a summary of what we know about the role that excitations of the gluonic field play in determining the spectrum of meson resonances. Recent studies using lattice techniques have suggested a phenomenology of gluonic excitations within QCD that leads to hybrid mesons with both exotic and non-exotic quantum numbers. I will discuss these calculations and describe their relationship to current experimental knowledge and to forthcoming experiments at Jefferson Lab and elsewhere.

Dudek, Jozef J. [ODU, JLAB

2014-06-01

366

Female reproductive steroids and neuronal excitability.  

PubMed

Oestrogen and progesterone have specific receptors in the central nervous system and are able to regulate neuronal development and plasticity, neuronal excitability, mitochondrial energy production, and neurotransmitter synthesis, release, and transport. On neuronal excitability, estradiol and progesterone seem to have an opposite effect, with estradiol being excitatory and progesterone and its derivative allopregnanolone being inhibitory. Estradiol augments N-methyl-D-aspartate-mediated glutamate receptor activity, while progesterone enhances gamma-aminobutyric acid-mediated chloride conductance. Sex steroid regulation of the balance of neuroexcitatory and neuroinhibitory activities may have a role in modulating clinical susceptibility to different neurological conditions such as migraine, catamenial epilepsy, premenstrual dysphoric disorder, and premenstrual syndrome. PMID:21533709

Finocchi, C; Ferrari, M

2011-05-01

367

Elementary spin excitations in ultrathin itinerant magnets  

NASA Astrophysics Data System (ADS)

Elementary spin excitations (magnons) play a fundamental role in condensed matter physics, since many phenomena e.g.magnetic ordering, electrical (as well as heat) transport properties, ultrafast magnetization processes, and most importantly electron/spin dynamics can only be understood when these quasi-particles are taken into consideration. In addition to their fundamental importance, magnons may also be used for information processing in modern spintronics. Here the concept of spin excitations in ultrathin itinerant magnets is discussed and reviewed. Starting with a historical introduction, different classes of magnons are introduced. Different theoretical treatments of spin excitations in solids are outlined. Interaction of spin-polarized electrons with a magnetic surface is discussed. It is shown that, based on the quantum mechanical conservation rules, a magnon can only be excited when a minority electron is injected into the system. While the magnon creation process is forbidden by majority electrons, the magnon annihilation process is allowed instead. These fundamental quantum mechanical selection rules, together with the strong interaction of electrons with matter, make the spin-polarized electron spectroscopies as appropriate tools to excite and probe the elementary spin excitations in low-dimensional magnets e.g ultrathin films and nanostructures. The focus is put on the experimental results obtained by spin-polarized electron energy loss spectroscopy and spin-polarized inelastic tunneling spectroscopy. The magnon dispersion relation, lifetime, group and phase velocity measured using these approaches in various ultrathin magnets are discussed in detail. The differences and similarities with respect to the bulk excitations are addressed. The role of the temperature, atomic structure, number of atomic layers, lattice strain, electronic complexes and hybridization at the interfaces are outlined. A possibility of simultaneous probing of magnons and phonons in complex low-dimensional ferromagnetic oxide nanostructures is discussed. The influence of the relativistic spin-orbit coupling on high-energy magnons is addressed. It is shown how the spin-orbit coupling breaks the energy degeneracy of the magnons excited in an ultrathin ferromagnet, and how it influences their lifetime, amplitude, group and phase velocity. A potential application of these new effects in modern spintronics is outlined. It is illustrated how one can take advantage of collective nature of magnons and use these quasi-particles for probing the magnetic exchange interaction at buried interfaces.

Zakeri, Khalil

2014-12-01

368

Exciting Baryons: now and in the future  

SciTech Connect

This is the final talk of NSTAR2011 conference. It is not a summary talk, but rather a looking forward to what still needs to be done in excited baryon physics. In particular, we need to hone our tools connecting experimental inputs with QCD. At present we rely on models that often have doubtful connections with the underlying theory, and this needs to be dramatically improved, if we are to reach definitive conclusions about the relevant degrees of freedom of excited baryons. Conclusions that we want to have by NSTAR2021.

Michael Pennington

2012-04-01

369

Science Signaling Podcast: 06 May 2008  

NSDL National Science Digital Library

This conversation is about research highlighted in Editors' Choice titled, "Whats So Exciting About Glia?" The highlighted article is R. Kradttir, N. B. Hamilton, Y. Bakiri, D. Attwell, Spiking and nonspiking classes of oligodendrocyte precursor glia in CNS white matter. Nat. Neurosci. 11, 450456 (2008). (Length: 6 min; file size: 2.61 MB; file format: mp3; location: http://podcasts.aaas.org/science_signaling/ScienceSignaling_080506.mp3)

Elizabeth M. Adler (American Association for the Advancement of Science; Science Signaling REV)

2008-05-06

370

Earth Sciences Division annual report 1989  

SciTech Connect

This Annual Report presents summaries of selected representative research activities from Lawrence Berkeley Laboratory grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrology, Geology and Geochemistry, and Geophysics and Geomechanics. We are proud to be able to bring you this report, which we hope will convey not only a description of the Division's scientific activities but also a sense of the enthusiasm and excitement present today in the Earth Sciences.

Not Available

1990-06-01

371

Large-excitability asymptotics for scroll waves in three-dimensional excitable media Daniel Margerit* and Dwight Barkley  

E-print Network

Large-excitability asymptotics for scroll waves in three-dimensional excitable media Daniel-dimensional scroll waves are considered in a reaction-diffusion model of excitable media in the large excitability limit. Coordinates based on the scroll filament are defined and shown to provide a natural extension

Barkley, Dwight

372

School News School of Science and Technology 2011  

E-print Network

School News School of Science and Technology 2011 #12;Welcome 2011 is an exciting time for students), the home to the School of Science and Technology, and students who have got involved with career enhancing activities alongside their studies (page 6). Don't miss our article on `Top 10 things you need to know before

Evans, Paul

373

Adventures in Rocket Science. EG-2007-12-179-MSFC  

ERIC Educational Resources Information Center

This guide was prepared as a tool useful for informal education venues (4-H, Boys and Girls Clubs, Boy Scouts, Girl Scouts, etc.), science clubs and related programs, and can be adopted for formal education settings. An exciting and productive study in rocket science can be implemented using the selected activities for the above-mentioned

Huegele, Vince; Hill, Kristy; Terry, Brenda

2008-01-01

374

Computer Animations a Science Teaching Aid: Contemplating an Effective Methodology  

ERIC Educational Resources Information Center

To improve quality of science education, the author suggests use of entertaining and exciting technique of animation for better understanding of scientific principles. Latest technologies are being used with more vigour to spread venomous superstitions. Better understanding of science may help students to better their scientific temper. Keeping

Tannu, Kirti

2008-01-01

375

"Celebrate Science" Has Formula for Hands-On Learning  

ERIC Educational Resources Information Center

Cost-effective, easily replicated program is a win-win situation for high schoolers who teach science and for their elementary students. The thank-you letter from Leslie, a grade-schooler in San Diego County's Ramona Unified School District, speaks volumes about the excitement generated by "Celebrate Science"--an innovative, standards-based

Brydolf, Carol

2012-01-01

376

College of Liberal Arts and Sciences Douglas Cook Award  

E-print Network

1 College of Liberal Arts and Sciences Douglas Cook Award for Entrepreneurship and Innovation Arts and Sciences Douglas Cook Award for Entrepreneurship and Innovation. We are excited to administer, and to provide resources to advance the proposals from ideas into the early stages of action. Individuals and

Gilbert, Matthew

377

Creating a computer science canon: a course of \\  

Microsoft Academic Search

Computer science has a reputation of being a discipline in a perpetual state of accelerated progress-a discipline in which our techniques, our hardware, our software systems, and our literature rarely exhibit a staying power of more than several years. While undeniably exciting, this state of continual intellectual upheaval can leave computer science students (and faculty) with a disturbing sense that

Michael Eisenberg

2003-01-01

378

Bridging Science and Policy: The AGU Science Policy Conference  

NASA Astrophysics Data System (ADS)

In recent years, science has become inextricably linked to the political process. As such, it is more important now than ever for science to forge a better relationship with politics, for the health of both science and society. To help meet this need, the American Geophysical Union (AGU) strives to engage its members, shape policy, and inform society about the excitement of Earth and space science and its role in developing solutions for the sustainability of the planet. In June 2013, AGU held its second annual Science Policy Conference in Washington, D.C. The goal of the conference is to provide a new forum for diverse discussions and viewpoints on the challenges and opportunities of science policy, with a focus on applications of Earth and space science that serve local, national, and international communities. The meeting brought together more than 300 scientists, policy makers, industry professionals, members of the press, and other stakeholders to discuss the topics concerning the Arctic, climate change, oceans, energy, technology and infrastructure, and natural hazards science as they relate to challenges impacting society. Sessions such as 'The Water-Energy Nexus,' 'Potential for Megadisasters,' 'The Changing Ocean and Impacts on Human Health,' and 'Drowning and Drought: Agricultural Impacts of Climate Change' are examples of some of the intriguing and timely science policy issues addressed at the conference. The findings from the conference were used to develop a summary report. The report highlights key facts and figures to be used as a resource in discussions with policy makers and other stakeholders regarding the conference topics. This presentation will discuss the goals and outcomes of the conference and how the event represents one of the many ways AGU is approaching its 'Science and Society' priority objective as part of the Union's strategic plan; namely by increasing the effectiveness and recognition of AGU among policy makers as an authoritative source of integrated, interdisciplinary Earth and space science information.

Hankin, E. R.; Uhlenbrock, K.; Landau, E. A.

2013-12-01

379

Science Matters  

ERIC Educational Resources Information Center

The spaces and structures used for undergraduate science often work against new teaching methods and fail to provide environments that attract the brightest students to science. The undergraduate science building often offers little to inspire the imaginations of young minds. The typical undergraduate science building also tends to work against

Odell, Bill

2005-01-01

380

Science Sacks  

ERIC Educational Resources Information Center

With the emphasis placed on standardized testing, science education has been squeezed out. As a physics teacher, the author knows the importance of building children's interest in science early in their school career and of providing practice in basic science skills and inquiry. In order to make more time for science at her sons' elementary

Freudenberg, Kimberlee

2012-01-01

381

Science Fictions  

Microsoft Academic Search

This paper argues that reading science fiction can help us understand contemporary debates in feminist psychology and envisage its future. It examines how science fiction, by extrapolating from accepted scientific realities, generates conceptual uncertainties which resemble those existing in feminist psychology around objectivity. The paper then explores how science fiction's stylistic uncertainties are paralleled in feminist psychology. Science fiction's suspensions

Corinne Squire

1991-01-01

382

Science Buddies.  

ERIC Educational Resources Information Center

Describes the science buddies program that pairs a 7th grade life science class with a 2nd or 3rd grade class in a yearlong partnership of science adventures. Includes sample activities and National Science Education Standards related to the activities. (Author/KHR)

Potenza, Susan Ade

2003-01-01

383

Local structural excitations in model glasses  

NASA Astrophysics Data System (ADS)

Structural excitations of model Lennard-Jones glass systems are investigated using the activation-relaxation technique (ARTn), which explores the potential energy landscape around a local minimum energy configuration by converging to a nearby saddle-point configuration. Performing ARTn results in a distribution of barrier energies that is single-peaked for well-relaxed samples. The present work characterizes such atomic-scale excitations in terms of their local structure and environment. It is found that, at zero applied stress, many of the identified events consist of chainlike excitations that can either be extended or ringlike in their geometry. The location and barrier energy of these saddle-point structures are found to correlate with the type of atom involved, and with spatial regions that have low Kelvin eigenshear moduli and are close to the excess free volume within the configuration. Such correlations are, however, weak and more generally the identified local structural excitations are seen to exist throughout the model glass sample. The work concludes with a discussion within the framework of ? and ? relaxation processes that are known to occur in the undercooled liquid regime.

Swayamjyoti, S.; Lffler, J. F.; Derlet, P. M.

2014-06-01

384

Corona Discharge in Nuclear Excited Dusty Plasma  

SciTech Connect

We considered the possibility of using a corona discharge in a nuclear excited dusty plasma to provide the stability of well ordered dusty plasma structures from a fissionable material and to accomplish a more efficient conversion of nuclear energy into radiation.

Deputatova, L. V.; Fortov, V. E.; Filinov, V. S.; Vladimirov, V. I.; Meshakin, V. I.; Rykov, V. A. [Joint Institute for High Temperatures RAS, Izhorskaya str. 13, bd. 2, Moscow (Russian Federation); Sinkevich, O. A. [Moscow Power Engineering Institute (Technical University) Krasnokazarmennaya str. 14, Moscow (Russian Federation)

2011-11-29

385

Coherent Rydberg Excitation in Thermal Microcells  

NASA Astrophysics Data System (ADS)

In order to create quantum devices based on the Rydberg blockade mechanism, it is necessary to have a confinement of the excitation volume to less than the blockade radius in a frozen gas of atoms; i.e. the excitation times need to be shorter than the timescales of the respective dephasing mechanisms. While ultracold gases seem to be the obvious choice, our approach utilizes thermal atomic vapor in small glass cells [1] which offer multiple advantages like good optical access and scalability. Such a system can be realized by confining the atoms to geometries in the micron regime. Decoherence effects like resonant interactions of the Rydberg atoms with polaritonic excitations in the glass have been studied and can be minimized by the appropriate choice of Rydberg states [2]. Using a bandwidth-limited pulsed laser system for the Rydberg excitation we observe coherent Rabi oscillations on the nanosecond timescale. In collaboration with Renate Daschner, Harald Kuebler, Bernhard Huber, Thomas Baluktsian, Andreas Koelle, James Shaffer, and Tilman Pfau. [4pt] [1] Baluktsian, T., et. al. Opt. Lett. 35, 1950 (2010) [0pt] [2] Kbler, H., et. al. Nature Photon. 4, 112-116 (2010)

Loew, Robert

2011-06-01

386

Excitation of XUV radiation in solar flares  

NASA Technical Reports Server (NTRS)

The goal of the proposed research was to understand the means by which XUV radiation in solar flares is excited, and to use this radiation as diagnostics of the energy release and transport processes occurring in the flare. Significant progress in both of these areas, as described, was made.

Emslie, A. Gordon

1992-01-01

387

Electrostatically excited diaphragm driven as a loudspeaker  

Microsoft Academic Search

This paper is focused on a hermetically sealed cavity which can be electrostatically excited and driven as a loudspeaker. The actuation principle is based on a diaphragm that is rolling against the cavity bottom to reach both large displacements and strong electrostatic forces. The loudspeaker is primarly intended for airborne ultrasound. Test speakers have been manufactured by micromachining in silicon

P. Rangsten; L. Smith; L. Rosengren; B. Hk

1996-01-01

388

On the excitation of Goodwin's oscillations  

NASA Astrophysics Data System (ADS)

We consider the necessary condition for excitation of long-periodic Goodwin's oscillations and short-periodic sawtooth oscillations in the Goodwin model with fixed delay in the induced investment. Also, using the method of equivalent linearization we evaluate the amplitude of steady-state oscillation.

Antonova, A. O.; Reznik, S. N.; Todorov, M. D.

2014-11-01

389

Electron Impact Excitation and Ionization of Neon  

NASA Astrophysics Data System (ADS)

We have further developed the B-Spline R-matrix (BSR) code [1] to allow for a large number of pseudo-states in the close-coupling expansion. In the present work, the BSRMPS approach [2] was employed to perform semi-relativistic (Breit-Pauli) close-coupling calculations for elastic scattering, excitation, and ionization of neon from both the ground state and the metastable excited states. Coupling to the ionization continuum through the pseudo-states is important for low-energy elastic scattering (to represent polarizability effects), for excitation in the ``intermediate'' energy regime of about 1-5 times the ionization potential, and to allow for the calculation of ionization processes by transforming the results obtained for excitation of the positive-energy pseudo-states. The current results represent a significant extension of our earlier near-threshold work [3] and previous non-relativistic RMPS calculations [4,5].[4pt] [1] O. Zatsarinny, Comp. Phys. Commun. 174 (2006) 273.[0pt] [2] O. Zatsarinny and K. Bartschat, Phys. Rev. Lett. 107 (2011) 023203.[0pt] [3] O. Zatsarinny and K. Bartschat, J. Phys. B 37 (2004) 2173.[0pt] [4] C. P. Ballance and D. C. Griffin, J. Phys. B 37 (2004) 2943.[0pt] [5] C. P. Ballance et al., J. Phys. B 37 (2004) 4779.

Zatsarinny, Oleg; Bartschat, Klaus

2012-10-01

390

Pedestrian excitation of bridges D E Newland  

E-print Network

of this phenomenon. By increasing modal damping, synchronization can be prevented, but how much damping is needed for stability Beff effective modal damping ratio 1 INTRODUCTION Since the pedestrian-excited vibration, it is possible to predict analytically the minimum damping required to ensure that synchronization does not lead

Newland, David E.

391

Ionic electrostatic excitations along biological membranes  

NASA Astrophysics Data System (ADS)

A theoretical analysis of ionic electrostatic excitations of a charged biological membrane is presented within the framework of the fluid theory for surface ions inside and outside the cell, in conjunction with the Poisson's equation. General expressions of dispersion relations are obtained for electrostatic oscillations of intrinsic cellular with different shapes and symmetries.

Moradi, Afshin

2011-02-01

392

Precision Dentistry Offers Exciting New Options  

E-print Network

Precision Dentistry Offers Exciting New Options UCSF Launches Center for Children's Oral Health / 2014 University of California, San Francisco magazine School of Dentistry #12;dentistry.ucsf.edu VOLUME 9 / 2014 Update > Featherstone Renewed as Dean for Five Years / PAGE 2 > UCSF Dentistry Joins All

Derisi, Joseph

393

Object-Oriented Programming: Regaining the Excitement  

E-print Network

Object-Oriented Programming: Regaining the Excitement Andrew P. Black Oregon Graduate Institute delivered at the ECOOP'98 Conference Banquet. It is not a literal transcription of my talk, since par- ticipants, and friends: Good evening. It's customary to start this kind of talk with a joke

Black, Andrew P.

394

Expectancy Induces Dynamic Modulation of Corticospinal Excitability  

Microsoft Academic Search

Behavioral studies using motor preparation paradigms have revealed that increased expectancy of a response signal shortens reaction times (RTs). Neurophysiological data suggest that in such paradigms, not only RT but also neuronal activity in the motor structures involved is modulated by expectancy of behaviorally relevant events. Here, we directly tested whether expectancy of a response signal modulates excitability of the

Gijs Van Elswijk; Bert U. Kleine; Sebastiaan Overeem; Dick F. Stegeman

2007-01-01

395

Spin excitations in pion inelastic scattering  

SciTech Connect

The data on spin excitations observed in pion inelastic scattering are reviewed. A predominant feature of this process is the selectivity with which high-spin unnatural-parity states are excited. Constant-q excitation functions have proven valuable in identifying unnatural-parity states because of the unique signature of ..delta..S = 1 transitions. It has recently been shown that angular distributions measured for transitions to natural-parity states are quite different for ..delta..S = 0 and ..delta..S = 1 transitions. Pion scattering should continue to prove useful in studying the spin structure of nuclear transitions because of the sensitivity of both excitation functions and angular distributions to the spin transferred to the nucleus. In particular, pion scattering measurements may be helpful in searches for spin-mode giant resonances. In addition to the ability to distinguish transitions dominated by ..delta..S = 1, comparisons of ..pi../sup +/ and ..pi../sup -/ scattering can be used to determine the relative contributions of neutrons and protons to inelastic transitions. In each N not equal to Z nucleus studied there have been large ..pi../sup +//..pi../sup -/, asymmetries observed for some transitions to stretched states. This results in information that is not obtainable from 180/sup 0/ electron scattering.

Seestrom-Morris, S.J.; Holtkamp, D.B.; Cottingame, W.B.

1982-01-01

396

Speech enhancement using excitation source information  

Microsoft Academic Search

This paper proposes an approach for processing speech from multiple microphones to enhance speech degraded by noise and reverberation. The approach is based on exploiting the features of the excitation source in speech production. In particular, the characteristics of voiced speech can be used to derive a coherently added signal from the linear prediction (LP) residuals of the degraded speech

B. Yegnanarayana; S. R. Mahadeva Prasanna; K. Sreenivasa Rao

2002-01-01

397

Supersolitons: Solitonic Excitations in Atomic Soliton Chains  

SciTech Connect

We show that, by tuning interactions in nonintegrable vector nonlinear Schroedinger equations modeling Bose-Einstein condensates and other relevant physical systems, it is possible to achieve a regime of elastic particlelike collisions between solitons. This would allow one to construct a Newton's cradle with solitons and supersolitons: localized collective excitations in solitary-wave chains.

Novoa, David; Michinel, Humberto [Area de Optica, Facultade de Ciencias, Universidade de Vigo, As Lagoas s/n, Ourense, E-32004 Spain (Spain); Malomed, Boris A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Perez-Garcia, Victor M. [Departamento de Matematicas, E.T.S.I. Industriales, and Instituto de Matematica Aplicada a la Ciencia y la Ingenieria, Universidad de Castilla-La Mancha, Avenida Camilo Jose Cela, 3, 13071 Ciudad Real (Spain)

2008-10-03

398

Remote changes in cortical excitability after stroke  

Microsoft Academic Search

Summary Changes in the cerebral metabolism and the excitability of brain areas remote from an ischaemic brain lesion have been reported in animals and humans and impli- cated as a mechanism relevant to functional recovery. The aim of the present study was to determine whether changes in the inhibitory and excitatory activity in motor cortex of the non-affected hemisphere are

Cathrin M. Butefisch; Johannes Netz; Rudiger J. Seitz; Volker Homberg

399

Power amplifier for ultrasonic transducer excitation  

Microsoft Academic Search

Design of the power amplifier for ultrasonic transducer excitation is presented. We assumed that the amplifier output impedance will be significantly lower than the transducer input impedance. Therefore we suggest to used the transformer as voltage step-up and impedance matching element. The transformer influence on the ultrasonic transducer bandwidth and the power transfer efficiency are analyzed using the Butterworth-Van Dyke

L. Svilainis

400

Contour Line Portraits: Excited about Artistic Abilities  

ERIC Educational Resources Information Center

In this article, the author describes a self-portrait project that encouraged students, boosted their self-confidence, and got them excited about their artistic abilities--while producing amazing results. This lesson effectively develops artistic ability by compelling students to see that drawing is quite simply breaking down objects into the

Neal, Kari Gertz

2012-01-01

401

Persistent Histamine Excitation of Glutamatergic Preoptic Neurons  

PubMed Central

Thermoregulatory neurons of the median preoptic nucleus (MnPO) represent a target at which histamine modulates body temperature. The mechanism by which histamine excites a population of MnPO neurons is not known. In this study it was found that histamine activated a cationic inward current and increased the intracellular Ca2+ concentration, actions that had a transient component as well as a sustained one that lasted for tens of minutes after removal of the agonist. The sustained component was blocked by TRPC channel blockers. Single-cell reverse transcription-PCR analysis revealed expression of TRPC1, TRPC5 and TRPC7 subunits in neurons excited by histamine. These studies also established the presence of transcripts for the glutamatergic marker Vglut2 and for the H1 histamine receptor in neurons excited by histamine. Intracellular application of antibodies directed against cytoplasmic sites of the TRPC1 or TRPC5 channel subunits decreased the histamine-induced inward current. The persistent inward current and elevation in intracellular Ca2+ concentration could be reversed by activating the PKA pathway. This data reveal a novel mechanism by which histamine induces persistent excitation and sustained intracellular Ca2+ elevation in glutamatergic MnPO neurons. PMID:23082195

Tabarean, Iustin V.

2012-01-01

402

Soapy Science. Teaching Science.  

ERIC Educational Resources Information Center

Describes a science and math activity that involves bubbles, shapes, colors, and solid geometry. Students build geometric shapes with soda straws and submerge the shapes in soapy water, allowing them to review basic geometry concepts, test hypotheses, and learn about other concepts such as diffraction, interference colors, and evaporation. (TJQ)

Leyden, Michael

1997-01-01

403

Computer Science Computer Science?  

E-print Network

in electrical engineering and computer science MSAIL: Artificial intelligence group HKN: Eta Kappa Nu honor and rescue. Future OutlookInnovative Tracks of Study Artificial Intelligence: Learn the fundamentals of AI tricks while participating in department-sponsored hackathons and programming contests, and at similar

Eustice, Ryan

404

Science Shorts: Spoilage Science  

NSDL National Science Digital Library

Whether it's fresh or processed, all food eventually spoils. Methods such as freezing, canning, and the use of preservatives lengthen the lifespan of foods, and we--and the modern food industry--rely on these methods to maintain our food supply. This month's Science Shorts explores the concepts of food spoilage and prevention.

2005-01-01

405

Science Outreach Science Outreach  

E-print Network

funds for the observatory and the Trottier Studio for Innovative Science Education where the majority and Motion, Human Anatomy, Lasers in Action, Life Under the Microscope, Math in Action, Electrophoresis and demos at school fairs, community events and classrooms. Math OutreachThese camps are designed to provide

406

Science Teaching to Fire the Imagination.  

ERIC Educational Resources Information Center

Presents a range of exciting ideas for encouraging active learning, for illuminating new concepts, and for making science lessons fun. Topics include modeling, matter, heat, diffusion, changes of state, heat transfer, energy changes, atomic structure, waves, gravity, enzymes, and habitats. (JRH)

Sandford, Diana; Fleetwood, Julie

1997-01-01

407

College of Agriculture and Life Sciences  

E-print Network

.....................................7 Keep up with all the exciting research, academic, and Extension news at the College of AgricultureRESEARCH College of Agriculture and Life Sciences http://news.cals.vt.edu/innovations Featured ..................................................... 5 Soil Judging Team digs into first place............ 7 extension INNOVATIONS Dean

Liskiewicz, Maciej

408

Biopolitical science.  

PubMed

This article develops a theoretical framework for biopolitical science as a science of political animals. This science moves through three levels of deep political history: the universal political history of the species, the cultural political history of the group, and the individual political history of animals in the group. To illustrate the particular application of biopolitical science, this essay shows how this science would help us to understand Abraham Lincoln's Emancipation Proclamation of January 1, 1863. PMID:20812796

Arnhart, Larry

2010-03-01

409

Tuned thalamic excitation is amplified by visual cortical circuits.  

PubMed

Cortical neurons in thalamic recipient layers receive excitation from the thalamus and the cortex. The relative contribution of these two sources of excitation to sensory tuning is poorly understood. We optogenetically silenced the visual cortex of mice to isolate thalamic excitation onto layer 4 neurons during visual stimulation. Thalamic excitation contributed to a third of the total excitation and was organized in spatially offset, yet overlapping, ON and OFF receptive fields. This receptive field structure predicted the orientation tuning of thalamic excitation. Finally, both thalamic and total excitation were similarly tuned to orientation and direction and had the same temporal phase relationship to the visual stimulus. Our results indicate that tuning of thalamic excitation is unlikely to be imparted by direction- or orientation-selective thalamic neurons and that a principal role of cortical circuits is to amplify tuned thalamic excitation. PMID:23933748

Lien, Anthony D; Scanziani, Massimo

2013-09-01

410

Tuned Thalamic Excitation is Amplified by Visual Cortical Circuits  

PubMed Central

Cortical neurons in thalamic recipient layers receive excitation from the thalamus and the cortex. The relative contribution of these two sources of excitation to sensory tuning is poorly understood. Here we optogenetically silence the visual cortex of mice to isolate thalamic excitation onto layer 4 neurons during visual stimulation. Thalamic excitation contributes to a third of total excitation and is organized in spatially offset, yet overlapping ON and OFF receptive fields. This receptive field structure predicts the orientation tuning of thalamic excitation. Finally, thalamic and total excitation are similarly tuned to orientation and direction, and have the same temporal phase relationship to the visual stimulus. Our results indicate that tuning of thalamic excitation is unlikely to be imparted by direction or orientation selective thalamic neurons and that a principal role of cortical circuits is to amplify tuned thalamic excitation. PMID:23933748

Lien, Anthony D.; Scanziani, Massimo

2013-01-01

411

Communicating Science through Exhibitions  

NASA Astrophysics Data System (ADS)

It is critically important for the public to better understand the scientific process. Museum exhibitions are an important part of informal science education that can effectively reach public audiences as well as school groups. They provide an important gateway for the public to learn about compelling scientific endeavors. Science exhibitions also provide a marvelous opportunity for scientists to become engaged in the exhibit development process. The Space Science Institute (SSI) is a national leader in producing traveling science exhibitions and their associated educational programming (i.e. interactive websites, educator workshops, public talks, instructional materials). The focus of this presentation will be on two of its exhibit projects: MarsQuest (on tour for four years) and Alien Earths (its tour began early in 2005). MarsQuest is enabling millions of Americans to share in the excitement of the scientific exploration of Mars and to learn more about their own planet in the process. Alien Earths will bring origins-related research and discoveries to students and the American public. It has four interrelated exhibit areas: Our Place in Space, Star Birth, Planet Quest, and Search for Life. Exhibit visitors will explore the awesome events surrounding the birth of stars and planets; they will join scientists in the hunt for planets outside our solar system including those that may be in ``habitable zones'' around other stars; and finally they will be able to learn about how scientists are looking for signs of life beyond Earth. SSI is also developing interactive web sites based on exhibit themes. New technologies are transforming the Web from a static medium to an interactive environment with tremendous potential for informal education and inquiry-based investigations. This talk will focus on the role informal science projects play in effectively communicating science to a broad, public audience.

Dusenbery, Paul

2005-04-01

412

Solar Astronomy as a Means to Promote Authentic Science Research in a Teacher Professional Development Program  

Microsoft Academic Search

Teacher Leaders in Research Based Science Education (TLRBSE) is an NSF-funded Teacher Enhancement Program hosted by the National Optical Astronomy Observatory (NOAO) in Tucson, AZ. Consistent with national priorities in education, TLRBSE seeks to retain and renew middle and high school science teachers. Within the exciting context of astronomy, TLRBSE integrates the best pedagogical practices of Research Based Science Education

C. E. Walker; S. Croft; S. M. Pompea; C. Plymate; D. McCarthy

2003-01-01

413

Good Things Are Happening in the College of Allied Health Sciences!  

E-print Network

Good Things Are Happening in the College of Allied Health Sciences! 1 College of Allied Health Sciences / utmem.edu The College of Allied Health Sciences has had two exciting events since moving to our for prospective students and family members interested in allied health careers. This is the first time

Cui, Yan

414

Communicating the science of the 11-year sunspot cycle to the general public  

NASA Astrophysics Data System (ADS)

Astrophysics is one branch of science which excites the imagination of the general public. Pioneer science popularizers like George Gamow and Fred Hoyle wrote on different aspects of astrophysics. However, of late, we see a trend which I find disturbing. While it has become extremely fashionable to write popular science books on cosmology, other areas of astrophysics are grossly neglected.

Choudhuri, A. R.

2015-03-01

415

Science as Performance: Communicating and Educating through Theater, Music, and Dance  

Microsoft Academic Search

Theater, music, dance, the literary and the visual arts can convey the joys and controversies of science. We describe a program at the Graduate Center entitled Science & the Arts which is designed to communicate to the public the excitement and wonder of science, technology, engineering and mathematics. Over the past few years there have been major successes in communicating

Brian B. Schwartz

2010-01-01

416

Company: Mad Science of West New Jersey Work Location: North Brunswick and surrounding areas  

E-print Network

Rate: $25/program + bonuses + Partial Mileage Reimbursement Type of Business: Science Education Job to excite children and convey to them that science surrounds them. We accomplish this by relating science and weekends to accommodate students' busy schedules. * Instructors gain experience executing lesson plans

Hanson, Stephen Jos

417

[Faculty of Science Information and Computing Sciences  

E-print Network

[Faculty of Science Information and Computing Sciences] Terminating combinator parsers in Agda and Computing Sciences Utrecht University June 12, 2008 #12;[Faculty of Science Information and Computing Sciences] 2 Overview Totality Parser combinators Terminating combinator parsers #12;[Faculty of Science

Lh, Andres

418

Inquiry: The Key to Exemplary Science  

NSDL National Science Digital Library

Science teachers aiming to foster inquiry in their classrooms will find the sixth title in the Exemplary Science monograph series, Inquiry: The Key to Exemplary Science full of helpful advice and new techniques. The 18 chapters in this monograph illustrate various forms of inquiry, offer detailed examples of planning and execution, and provide case studies highlighting successful implementation of inquiry. Student learning, development of positive attitudes, the ability to use concepts and skills in completely new situations are all demonstrated for use in your classroom. The National Science Education Standards call "for every student (every year) to experience the richness and excitement of knowing and understanding the natural world." Editor Robert Yager notes that "in one sense, inquiry can be used as a synonym for science. Both include starting with questions, collecting evidence concerning the explanations offered, and arguing with others about the validity of the explanations. Science is a continuing quest for better understanding of the natural universe. This quest is inquiry!

2009-04-01

419

Exciting Students through VEX Robotic Competitions  

ERIC Educational Resources Information Center

Robotic competitions continue to gain popularity in the educational community as a way to engage students in hands-on learning that can raise a student's interest in science, technology, engineering, and mathematics. In 1992, For Inspiration and Recognition of Science and Technology (FIRST) held its first competition and presented a style of

Robinson, Trevor P.; Stewardson, Gary A.

2012-01-01

420

Faculty of Science Computer Science  

E-print Network

Faculty of Science Computer Science Software engineering, network and system analysis continue a variety of computer science programs to prepare students for a career in the technology industry or in research and academia. A computer science degree provides an in-depth understanding of the fundamentals

421

Faculty of Science Computer Science  

E-print Network

Faculty of Science Computer Science Computer software engineering, network and system analysis.uwindsor.ca/computerscience The University of Windsor offers a variety of computer science programs to prepare students for a career in the technology industry or in research and academia. A computer science degree provides an in-depth understanding

422

Earth Sciences Environmental Earth Sciences,  

E-print Network

84 Earth Sciences­ Environmental Earth Sciences, Geology MGeol (Single Honours Degrees) Earth Sciences BSc (Single Honours Degrees) Environmental Earth Sciences Geology BSc (Joint Honours Degrees) and among the most research-intensive in Europe. Features * The Department of Earth and Environmental

Brierley, Andrew

423

Science Fiction and Science Education.  

ERIC Educational Resources Information Center

Uses science fiction films such as "Jurassic Park" or "Anaconda" to teach science concepts while fostering student interest. Advocates science fiction as a teaching tool to improve learning and motivation. Describes how to use science fiction in the classroom with the sample activity Twister. (YDS)

Cavanaugh, Terence

2002-01-01

424

Influence of the drugs for membrane excitability modification on the excitation caused by achatin-I.  

PubMed

1. The pneumatic pressure ejection of achatin-I (Gly-D-Phe-L-Ala-L-Asp), an endogenous tetrapeptide having a D-phenylalanine residue, produced an inward current (Iin) in an identifiable giant neuron, PON (periodically oscillating neuron), of an African giant snail, Achatina fulica Frussac. The influence of the drugs for membrane excitability modification, applied by perfusion, on the PON excitation caused by achatin-I was examined under voltage clamp. 2. The four channel blocking drugs, tetrodotoxin (TTX), tetraethylammonium chloride (TEA), verapamil and picrotoxin, at 10(-4) M did not affect significantly the PON excitation caused by the peptide. 3. N-beta-phenylpropionyl-L-tyrosine (BPLT), a membrane hyperpolarizant, at 10(-6) M and concanavalin A (Con A), which altered the response to L-glutamate, at 100 micrograms/ml-1 were considered to hardly influence the PON excitation caused by achatin-I. PMID:7690319

Santos, D E; Takeuchi, H

1993-06-01

425

Optimization of Two-photon Excited Fluorescence Enhancement between Tunable and Broadband Femtosecond Laser Pulse Excitations  

E-print Network

140 fs pulse excitations using three dye-phantoms (Indo-1, FITC, and TRITC) representative of fluorescent probes with similar TPEF characteristics. The integrated experimental system, with custom-designed GDD compensation, dispersion-less laser...

Wang, Chao

2012-02-14

426

Excitation energy relaxation in model aggregates of photosynthetic pigments upon picosecond laser excitation  

NASA Astrophysics Data System (ADS)

The methods of picosecond absorption spectroscopy require theuse of sufficiently high laser pulse intensities because of low sensitivity of these methods. The excitation of aggregated systems containing a large number of interacting chromophores, localized in a small volume, by intense laser pulses may lead to side effects which are observed as changes in absorption spectra but are not connected with the processes of electronic excitation energy relaxation. In this paper we present the results of such investigations through the examples of polymer ordered aggregates of photosynthetic pigments (chlorophyll, protochlorophyll, pheophytin) in binary mixtures of water with organic solvent (T=293 K) upon excitation by 20 ps pulses. The observable reversible spectral changes in ps and ns time scales are attributed to the effects of laser heating, rather than to the population of aggregate excited electronic states.

Chirvony, Vladimir S.; Zenkevich, Eduard I.; Gadonas, Roaldas; Krasauskas, V.; Pelakauskas, A.

1991-05-01

427

Peroxyacetyl radical: Electronic excitation energies, fundamental vibrational frequencies, and symmetry breaking in the first excited state  

NASA Astrophysics Data System (ADS)

Peroxyacetyl radical [CH3C(O)O2] is among the most abundant peroxy radicals in the atmosphere and is involved in OH-radical recycling along with peroxyacetyl nitrate formation. Herein, the ground ( X ) and first ( A ) excited state surfaces of cis and trans peroxyacetyl radical are characterized using high-level ab initio methods. Geometries, anharmonic vibrational frequencies, and adiabatic excitation energies extrapolated to the complete basis-set limit are reported from computations with coupled-cluster theory. Excitation of the trans conformer is found to induce a symmetry-breaking conformational change due to second-order Jahn-Teller interactions with higher-lying excited states. Additional benchmark computations are provided to aid future theoretical work on peroxy radicals.

Copan, Andreas V.; Wiens, Avery E.; Nowara, Ewa M.; Schaefer, Henry F.; Agarwal, Jay

2015-02-01

428

Space-Based Science and the American Competitiveness Initiative  

NASA Astrophysics Data System (ADS)

I discuss the process by which science contributes to the setting of government priorities, and how these priorities get translated into programs and budgets at the federal agencies that fund scientific research. New technologies are now opening exciting scientific opportunities across the biological and physical sciences. I review the motivations and goals of President Bush's American Competitiveness Initiative (ACI), the importance of societal relevance to federal investments in basic research, and the ACI's impacts on discovery-oriented disciplines within the physical sciences.

Marburger, John H.

429

Be/X-Ray Pulsar Binary Science with LOFT  

NASA Technical Reports Server (NTRS)

Accretion disks are ubiquitous in astronomical sources. Accretion powered pulsars are a good test bed for accretion disk physics, because unlike for other objects, the spin of the neutron star is directly observable allowing us to see the effects of angular momentum transfer onto the pulsar. The combination of a sensitive wide-field monitor and the large area detector on LOFT will enable new detailed studies of accretion powered pulsars which I will review. RXTE observations have shown an unusually high number of Be/X-ray pulsar binaries in the SMC. Unlike binaries in the Milky Way, these systems are all at the same distance, allowing detailed population studies using the sensitive LOFT WFM, potentially providing connections to star formation episodes. For Galactic accreting pulsar systems, LOFT will allow measurement of spectral variations within individual pulses, mapping the accretion column in detail for the first time. LOFT will also provide better constraints on magnetic fields in accreting pulsars, allowing measurements of cyclotron features, observations of transitions into the centrifugal inhibition regime, and monitoring of spin-up rate vs flux correlations. Coordinated multi-wavelength observations are crucial to extracting the best science from LOFT from these and numerous other objects.

Wilson-Hodge, Colleen A.

2011-01-01

430

Study of single-electron excitations by electron microscopy I. Image contrast from delocalized excitations  

Microsoft Academic Search

The inelastic scattering of fast electrons by the excitation of L-shell electrons at a stacking fault in silicon has been studied with a scanning transmission electron microscope. It was found that the bright-field stacking fault contrast is preserved in the filtered L-shell-loss signal at 100 eV. This result is discussed in terms of the delocalization of the excitation mechanism. It

A. J. Craven; J. M. Gibson; A. Howie; D. R. Spalding

1978-01-01

431

Understanding Science  

NSDL National Science Digital Library

The mission of the Understanding Science website is "to provide a fun, accessible, and free resource that accurately communicates what science is and how it really works." The project has a specific focus on assisting teachers in keeping young people interested in science; to support this goal, the site includes a range of materials for teachers. Visitors can start with the Site Tour area to learn about the structure and organization of the site. Moving along, the Understanding Science 101 area includes quick reviews of topics like How Science Works, What is Science?, and Why Science Matters. The Resource Library contains classroom activities, teaching tools, and strategies for keeping students thinking and engaged. Visitors can also use the Correcting Misconceptions area to address certain commonly held beliefs like Science is complete or Science is a collection of facts. Finally, visitors can sign up to receive updates when the site adds new information.

2012-08-17

432

Excitation and photon decay of giant resonances excited by intermediate energy heavy ions  

SciTech Connect

Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon /sup 17/O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the /sup 208/Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab.

Bertrand, F.E.; Beene, J.R.

1987-01-01

433

A scalable piezoelectric impulse-excited energy harvester for human body excitation  

NASA Astrophysics Data System (ADS)

Harvesting energy from low-frequency and non-harmonic excitations typical of human motion presents specific challenges. While resonant devices do have an advantage in environments where the excitation frequency is constant, and while they can make use of the entire proof mass travel range in the case of excitation amplitudes that are smaller than the internal displacement limit, they are not suitable for body applications since the frequencies are random and the amplitudes tend to be larger than the device size. In this paper a piezoelectric, impulse-excited approach is presented. A cylindrical proof mass actuates an array of piezoelectric bi-morph beams through magnetic attraction. After the initial excitation these transducers are left to vibrate at their natural frequency. This increases the operational frequency range as well as the electromechanical coupling. The principle of impulse excitation is discussed and a centimetre-scale functional model is introduced as a proof of concept. The obtained data show the influence of varying the frequency, acceleration and proof mass. Finally, a commercially available integrated circuit for voltage regulation is tested. At a frequency of 2 Hz and an acceleration of 2.7 m s-2 a maximal power output of 2.1 mW was achieved.

Pillatsch, P.; Yeatman, E. M.; Holmes, A. S.

2012-11-01

434

Excitation strengths in 109Sn: Single-neutron and collective excitations near 100Sn  

NASA Astrophysics Data System (ADS)

A set of B(E2) values for the low-lying excited states in the radioactive isotope 109Sn were deduced from a Coulomb excitation experiment. The 2.87-MeV/u radioactive beam was produced at the REX-ISOLDE facility at CERN and was incident on a secondary 58Ni target. The B(E2) values were determined using the known 2+?0+ reduced transition probability in 58Ni as normalization with the semiclassical Coulomb excitation code gosia2. The transition probabilities are compared to shell-model calculations based on a realistic nucleon-nucleon interaction and the predictions of a simple core-excitation model. This measurement represents the first determination of multiple B(E2) values in a light Sn nucleus using the Coulomb excitation technique with low-energy radioactive beams. The results provide constraints for the single-neutron states relative to 100Sn and also indicate the importance of both single-neutron and collective excitations in the light Sn isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekstrm, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhuser, R.; Grgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2012-09-01

435

High resolution fluorescent bio-imaging with electron beam excitation.  

PubMed

We have developed electron beam excitation assisted (EXA) optical microscope[1-3], and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.Figure1(a) shows schematic diagram of the proposed EXA microscope. An electron beam is focused on a luminescent film. A specimen is put on the luminescent film directly. The inset in Fig.1(a) shows magnified image of the luminescent film and the specimen. Nanometric light source is excited in the luminescent film by the focused electron beam. The nanometric light source illuminates the specimen, and the scattered or transmitted radiation is detected with a photomultiplier tube (PMT). The light source is scanned by scanning of the focused electron beam in order to construct on image. Figure1(b) shows a luminescence image of the cells acquired with the EXA microscope, and Fig.1(c) shows a phase contrast microscope image. Cells were observed in culture solution without any treatments, such as fixation and drying. The shape of each cell was clearly recognized and some bright spots were observed in cells. We believe that the bright spots indicated with arrows were auto-fluorescence of intracellular granules and light- grey regions were auto-fluorescence of cell membranes. It is clearly demonstrated that the EXA microscope is useful tool for observation of living biological cells in physiological conditions.jmicro;63/suppl_1/i16/DFU090F1F1DFU090F1Fig. 1.(a) Optical setup of EXA microscpe, and observation results of of living MARCO-expressing CHO cells with (b) EXA microscope and (c) phase contrast microscope. We proposed the EXA microscope as a technique with high spatial resolution beyond the diffraction limit of light. A spatial resolution greater than 100 nm was achieved for the EXA microscope and the dynamic behavior of moving nanoparticles in water was observed by time lapse imaging. We also demonstrated luminescence image of living cells in culture solution without any treatments. PMID:25359807

Kawata, Yoshimasa; Nawa, Yasunori; Inami, Wataru

2014-11-01

436

iBiology: communicating the process of science  

PubMed Central

The Internet hosts an abundance of science video resources aimed at communicating scientific knowledge, including webinars, massive open online courses, and TED talks. Although these videos are efficient at disseminating information for diverse types of users, they often do not demonstrate the process of doing science, the excitement of scientific discovery, or how new scientific knowledge is developed. iBiology (www.ibiology.org), a project that creates open-access science videos about biology research and science-related topics, seeks to fill this need by producing videos by science leaders that make their ideas, stories, and experiences available to anyone with an Internet connection. PMID:25080124

Goodwin, Sarah S.

2014-01-01

437

Science Standards  

NSDL National Science Digital Library

The Asia-Pacific Economic Cooperation (APEC) has created a Web site that offers English translations of the academic standards of Asian countries. This is a good way to compare U.S. science standards to Asian and Asia Pacific countries. Science standards are typically organized into three content areas: Earth and space sciences, life sciences, and physical sciences. Standards may also develop desired abilities or performance skill strands such as conceptual understanding, theorizing and analyzing, solving problems, communicating, and using tools, processes and procedures. This site allows for comparison of science standards between Australia, Japan, Korea, Malaysia, New Zealand, Singapore, Chinese Taipei, and the United States.

438

HEASARC - The High Energy Astrophysics Science Archive Research Center  

NASA Technical Reports Server (NTRS)

The High Energy Astrophysics Science Archive Research Center (HEASARC) is NASA's archive for high-energy astrophysics and cosmic microwave background (CMB) data, supporting the broad science goals of NASA's Physics of the Cosmos theme. It provides vital scientific infrastructure to the community by standardizing science data formats and analysis programs, providing open access to NASA resources, and implementing powerful archive interfaces. Over the next five years the HEASARC will ingest observations from up to 12 operating missions, while serving data from these and over 30 archival missions to the community. The HEASARC archive presently contains over 37 TB of data, and will contain over 60 TB by the end of 2014. The HEASARC continues to secure major cost savings for NASA missions, providing a reusable mission-independent framework for reducing, analyzing, and archiving data. This approach was recognized in the NRC Portals to the Universe report (2007) as one of the HEASARC's great strengths. This poster describes the past and current activities of the HEASARC and our anticipated developments in coming years. These include preparations to support upcoming high energy missions (NuSTAR, Astro-H, GEMS) and ground-based and sub-orbital CMB experiments, as well as continued support of missions currently operating (Chandra, Fermi, RXTE, Suzaku, Swift, XMM-Newton and INTEGRAL). In 2012 the HEASARC (which now includes LAMBDA) will support the final nine-year WMAP data release. The HEASARC is also upgrading its archive querying and retrieval software with the new Xamin system in early release - and building on opportunities afforded by the growth of the Virtual Observatory and recent developments in virtual environments and cloud computing.

Smale, Alan P.

2011-01-01

439

Electron excitation of a Jovian Aurora  

NASA Technical Reports Server (NTRS)

Because Jupiter possesses a magnetic field, auroral activity is very likely. The auroral emissions due to electron precipitation are estimated for a model atmosphere with and without helium. The incident primary electrons, which are characterized by representative spectra, are degraded in energy by applying the continuous slow down approximation. All secondaries, tertiaries, and higher generation electrons are assumed to be absorbed locally. A compilation of excitation, dissociation, and ionization cross section data for H, H2, and He are used to model all aspects of the energy deposition process. Volume emission rates are calculated from the total direct excitation rates, and appropriate corrections for cascading are applied. Helium emissions are relatively small because the majority of electrons are absorbed above the region of maximum He concentration.

Heaps, M. G.; Bass, J. N.; Green, A. E. S.

1973-01-01

440

Optimization of plasmon excitation at structured apertures.  

PubMed

Surface plasmon excitation that is due to a single or a structured circular aperture in a flat metallic screen is investigated theoretically and numerically with a view to enhancing the electric field close to the metallic surface. A systematic study of the homogeneous solution of the electromagnetic scattering problem is made with cylindrical coordinates, expanding Maxwell equations on a Fourier-Bessel basis. A perturbation analysis devoted to simple physical analyses of different types of cylindrical nanostructure is developed for the optimization of plasmon excitation by a normally incident linearly polarized monochromatic plane wave. The conclusions drawn from this analysis agree well with the results of rigorous electromagnetic calculations obtained with the differential theory of diffraction in cylindrical coordinates. PMID:16240501

Popov, Evgeny; Nevire, Michel; Fehrembach, Anne-Laure; Bonod, Nicolas

2005-10-10

441

Electrical Excitation of Surface Plasmon Polaritons  

NASA Astrophysics Data System (ADS)

A surface plasmon polariton (SPP) is an electromagnetic wave propagating at the interface between a metal and a dielectric material. The two-dimensional confinement of SPPs and the tunability of their dispersion enable optical functionality that cannot be achieved with regular dielectrics. Several novel concepts for sensing and opto-electronic integration based on SPPs have been proposed. In nearly all applications, as well as experiments based on SPPs, far-field excitation of SPPs is used, leading to bulky device designs. This thesis presents an electrically excitable source for SPPs that can be integrated in small, chip-size devices to enable the full application potential of SPPs. The device is based on a dielectric/metal geometry in which silicon quantum dots are placed in the near-field of the SPP mode. The quantum dots are electrically excited and decay by the generation of SPPs. Silicon quantum dots in silica are made by a magnetron sputtering technique, followed by annealing. From photoluminescence spectra as well as lifetime measurements we conclude that well-passivated Si quantum dots with quantum confined luminescence around 800 nm can be made. An electrical injection geometry is presented and electroluminescence is observed around 650 nm under a bias of 15-30 V. Strong bleaching of the quantum dot luminescence is observed under 0.5-20 keV electron beam irradiation, which has a potential consequence for the use of electron beam lithography in nanofabrication of structures with Si quantum dots. We describe the design and the fabrication of an electrically excitable plasmon source based on an insulator-metal-insulator (IMI) geometry. The coupling of quantum dots to the SPP mode was studied theoretically. For quantum dots spaced 20-200 nm away from the metal surface, more than 50% of the decay is into SPPs. An IMI SPP geometry for electrical excitation was fabricated using gold and silica doped with Si quantum dots as dielectric material. An IMI SPP source in the infrared region was fabricated by incorporating erbium in the dielectric material. Using an SPP waveguide coupled to the source, with suitable engineered outcoupling gratings, we observed the propagation and outcoupling of electrically excited SPPs. The optical properties of Si quantum dots in alumina are studied. This material is deposited by using CMOS compatible, low-temperature techniques of atomic layer deposition (ALD) and low pressure chemical vapor deposition (LPCVD). Quantum-confined photo- and electroluminescence is observed at 700-900 nm. This material is used in a novel metal-insulator-metal (MIM) geometry. SPPs are electrically excited and propagate inside the MIM geometry and are radiated into the far-field by an outcoupling structure. The radiated intensity decays for outcoupling structures further away from the excitation source. The obtained propagation length is = 4.4 0.6 micron, which is in good agreement with the expected propagation length based on measured values of the dielectric constants. The last chapter of this thesis reports on several application ideas for the electrical SPP sources presented in this thesis. Integrated lab-on-a-chip devices, plasmonic (bio)sensors, nanoscale photonic integrated circuits, and a novel quantum dot solar cell geometry are proposed.

van Loon, R. V. A.

2009-02-01

442

Excitation of millimeter and submillimeter water masers  

NASA Technical Reports Server (NTRS)

The excitation of maser emission in millimeter and submillimeter transitions of interstellar and circumstellar water is considered. An escape probability method is used to determine the equilibrium populations in 349 rotational states of both ortho- and para-water under varying conditions of gas temperature, density, water abundance, and radiation field. It is shown that, under those conditions believed to prevail around late-type stars and within star-forming regions, strong millimeter and submillimeter water maser emission can be generated by collisional excitations by H2. Several maser transitions can have strengths close to that of the 22 GHz line. The water maser line which can be observed from mountaintop facilities and those which will require air- or space-borne platforms are indicated. The exact portion of parameter space in which each maser transition exhibits peak emission is shown.

Neufeld, David A.; Melnick, Gary J.

1991-01-01

443

The tongue as an excitable medium  

NASA Astrophysics Data System (ADS)

Geographic tongue (GT) is a medical condition affecting approximately 2% of the population, whereby the papillae covering the upper part of the tongue are lost due to a slowly expanding inflammation. The resultant dynamical appearance of the tongue has striking similarities with well known out-of-equilibrium phenomena observed in excitable media, such as forest fires, cardiac dynamics, chemically driven reaction-diffusion systems and morphogenesis in multicellular organisms. Here we identify GT as a novel example of excitable media dynamics and explore the evolution of the condition from a dynamical systems perspective. We focus on two characteristic aspects of GT in particular: anisotropic expansion of lesions and re-entry of the inflammation into recovering regions. Our investigation sheds light on the evolution of the inflammation and suggests a practical way to classify the severity of the condition, based on the characteristic patterns observed in GT patients.

Seiden, Gabriel; Curland, Sofia

2015-03-01

444

Electron-impact excitation of neutral oxygen  

E-print Network

Aims: To calculate transition rates from ground and excited states in neutral oxygen atoms due to electron collisions for non-LTE modelling of oxygen in late-type stellar atmospheres, thus enabling reliable interpretation of oxygen lines in stellar spectra. Methods: A 38-state R-matrix calculation in LS-coupling has been performed. Basis orbitals from the literature (Thomas et al.) are adopted, and a large set of configurations are included to obtain good representations of the target wavefunctions. Rate coefficients are calculated by averaging over a Maxwellian velocity distribution. Results: Estimates for the cross sections and rate coefficients are presented for transitions between the seven lowest LS states of neutral oxygen. The cross sections for excitation from the ground state compare well with existing experimental and recent theoretical results.

P. S. Barklem

2006-09-25

445

Multiple excitation modes in 163Hf  

NASA Astrophysics Data System (ADS)

Excited states of 163Hf were populated using the 94Zr(74Ge,5 n ) reaction and the decay ? rays were measured with the Gammasphere spectrometer. Two previously known bands were extended to higher spins, and nine new bands were identified. In addition to bands associated with three- and five-quasiparticle configurations, two ? - vibrational bands coupled to the i13 /2 excitation were also observed. The lowest level of a newly identified, negative-parity band is proposed to be the ground state of the nucleus. A systematic delay of the high-spin proton crossing frequency with increasing quadrupole deformation from 162Hf to 172Hf was established. Extensive band searches failed to reveal a triaxial, strongly deformed structure in 163Hf similar to the one observed in several nuclei around A 165 .

Yadav, R. B.; Ma, W. C.; Marsh, J. C.; Ijaz, Q. A.; Janssens, R. V. F.; Carpenter, M. P.; Hoffman, C. R.; Lauritsen, T.; Zhu, S.; Kondev, F. G.; Grdal, G.; Hagemann, G. B.; Hartley, D. J.; Riedinger, L. L.; Mukhopadhyay, S.

2014-11-01

446

Nuclear level excitation during charge nonconservation  

SciTech Connect

The possibility of nuclei being excited during charge nonconservation was investigated. The process studied is analogous to nuclear K capture which does not change a nucleon's charge state but which does leave the nucleus in an excited state. We searched for ..gamma.. rays emitted by /sup 127/I nuclei and detected in a 25.4 cm x 20.3 cm diam NaI(Tl) counter. Our most conservative limit for the charge nonconserving lifetime tau/sub CNC/ for this mechanism is tau/sub CNC/greater than or equal to1.9 x 10/sup 21/ yr. The results can be used to place limits on the charge nonconservation mechanism in weak interactions where a neutrino replaces an electron in the (e,e) current, and where a proton replaces a neutron in the (p,n) current.

Holjevic-acute-accent, S.; Logan, B.A.; Ljubiic-acute-accent, A.

1987-01-01

447

Acylgermanes: Excited state processes and reactivity  

NASA Astrophysics Data System (ADS)

The excited state processes of an acetyltriphenylgermane as well as the generation and the reactivity of the germyl radical are studied by laser flash photolysis, ESR spin trapping experiments and MO calculations. The transient spectra, the dissociation quantum yield, the singlet excited state S 1 lifetime, the S 1 quenching by an iodonium salt, the triplet state energy level ET, the Ge-C bond dissociation energy BDE, the interaction of the germyl radical with oxygen, double bonds and an iodonium salt, and the ESR spectra are determined. A triplet cleavage process is clearly evidenced; a singlet cleavage should likely contribute. The overall reactivity is discussed and compared to that of parent compounds. The acetyltriphenylgermane behaves as a high performance photoinitiator in the free radical polymerization and free radical promoted cationic polymerizations.

Laleve, J.; Allonas, X.; Fouassier, J. P.

2009-02-01

448

Excitability in laser systems: The experimental side  

NASA Astrophysics Data System (ADS)

The main goal of this contribution is to give an insight into one of the most beautiful experiences: to be an experimentalist in Nonlinear Dynamics. In particular, I will refer to my field of expertise of Experimental Nonlinear Dynamics in Optical Systems. However, the great property of Nonlinear Dynamics is that the results are usually valid for different subjects ranging from biology to economics, and from physics to administration (to mention just those that we may consider opposite in spirit). With this in mind, you will be able to transfer many things I will write about to other fields, even to theoretical physics! The second goal is to describe how to interpret data and how to link it to general concepts of Nonlinear Dynamics. Third and last goal (but not less important) is to show that Experimental Nonlinear Dynamics is one of the most exciting fields in Physics and Mathematics. For this reason I will limit the discussions to a phenomenon called excitability.

Tredicce, Jorge R.

2000-12-01

449

Calculations of coincident ionization plus excitation  

SciTech Connect

For Li- and Be-like ions, K x-ray yields, together with detection that the ionic charge has increased, give the cross section for ionization plus excitation (IE), a process which can exhibit electron-electron correlations. Measurements of IE for /sub 14/Si/sup 11 +/ + He stimulated our coupled-channels calculations in the independent-Fermi-particle model (IFPM), which includes Pauli correlations. We discuss how the IFPM expressions, generalized here to include an open shell, differ from those for distinguishable electrons. The sensitivity of sigma/sub IE/ to correlations is shown. Recent additional measurements and future ones giving excitation functions for resolved configurations and complementary Auger data will provide even more sensitive tests of collisional correlation theory. 15 refs., 3 figs., 1 tab.

Becker, R.L.

1986-01-01

450

The excitation of O2 in auroras.  

NASA Technical Reports Server (NTRS)

Newly measured electron impact cross sections for excitation of the a super 1 Delta sub g and b super 1 Sigma (plus) sub g electronic states of O2 have been employed to predict the absolute volume emission rates from these states under auroral conditions. A secondary electron flux typical of an IBC II nighttime aurora was used, and the most important quenching processes were included in the calculations. The new excitation cross sections for the a super 1 Delta sub g and b super 1 Sigma (plus) sub g states are more than an order of magnitude larger than previous estimates and lead to correspondingly greater intensities in the atmospheric and IR atmospheric band systems. The calculated intensity ratios of the volume emission rates of 7621 A and 1.27 micron to that for 3914 A are smaller than those obtained from aircraft observations and recent rocket experiments.

Cartwright, D. C.; Trajmar, S.; Williams, W.

1972-01-01

451

Photodissociation and rotational excitation of interstellar CO.  

NASA Astrophysics Data System (ADS)

We have developed a detailed interstellar cloud model that takes into account the chemistry among simple carbon and oxygen bearing molecules, as well as ^13^C and ^18^O isotopic compounds. The rotational population of H_2_, CO, ^13^CO and C^18^O and the fine structure excitation of C, C^+^ and O are controlled by chemical processes, including selective photodissociation which depends on the rotational quantum number J, collisional and radiative processes allowing for photon trapping of CO millimeter and sub-millimeter lines. The gas and grain temperature distributions are obtained by solving a thermal equilibrium equation for each component. Comparison with the previous model calculations of van Dishoeck & Black (1988) and Le Bourlot et al. (1993) are made throughout the paper. We have computed series of models for three kinds of quiescent interstellar clouds: diffuse, translucent and dense dark clouds. The variations of the photodissociation rates are mainly controlled by self-shielding effects leading to a rotational selective photodissociation, i.e. a strong dependence on the rotational quantum number J: the more populated the level the more efficient is the self-shielding and the more rapid is the decrease of its photodissociation rate. This implies a strong coupling between photodissociation and rotational excitation, which has for main consequence to overpopulate low-lying levels and to under populate excited levels with respect to an LTE calculation. Under the combined influence of the rotational photodissociation and the inefficiency of collisions to populate excited levels, at the densities and temperatures prevailing in most clouds, the rotational population of CO and its isotopes is sub-thermally excited, except for the first two rotational levels of the three isotopes and the levels J=2 and 3 of the main isotope which are thermalized in the inner part of dark clouds. Photo-electric emission of electrons from grains is the dominant heating process in regions where UV photons are present, i.e. in diffuse and translucent clouds and in the outer parts of dark clouds. It is replaced by cosmic ray ionization of atomic and molecular hydrogen as a dominant heating process in the core of dark clouds. The cooling efficiency is entirely correlated to the cloud composition, with cooling dominated by fine structure excitation of C^+^ and rotational excitation of CO in diffuse and dark clouds, respectively; fine structure excitation of C contributes to the cooling of translucent clouds. The strong dependence of the temperature distribution in interstellar clouds on the external UV radiation field is emphasized. Our model calculations have been confronted with selected CO surveys of molecular clouds by Frerking et al. (1982), Cernicharo & Guelin (1987) and Lada et al. (1994). For that purpose, we have run series of model with various visual extinctions and densities covering a large range of values, from diffuse to dense cloud conditions. The temperature distribution was obtained by solving the thermal balance equation. The model predicts emissivities of the 1->0 line of CO well below the observations with the exception of the C^18^O(1->0) line in the the molecular clouds surveyed by Frerking et al. (1982) for which agreement between theory and observations is very good. Although the model predicts too low abundances of both ^13^CO and C^18^O, the column density ratio R(^13^CO/C^18^O) normalized to the isotopic ratio that we compute is in fairly good qualitative agreement with the one derived by Lada et al (1994) in the IC 5146 molecular cloud. The model calculations have also been used to predict the emissivities of the CO, ^13^CO, C^18^O, C and C^+^ lines under various interstellar conditions.

Warin, S.; Benayoun, J. J.; Viala, Y. P.

1996-04-01

452

String excitation inside generic black holes  

E-print Network

We calculate how much a first-quantized string is excited after crossing the inner horizon of charged Vaidya solutions, as a simple model of generic black holes. To quantize a string suitably, we first show that the metric is approximated by a {\\it plane-wave} metric near the inner horizon when the surface gravity of the horizon $\\kappa_I$ is small enough. Next, it is analytically shown that the string crossing the inner horizon is excited infinitely in an asymptotically flat spacetime, while it is finite in an asymptotically de Sitter spacetime and the string can pass across the inner horizon when $\\kappa_I<2\\kappa:= 2 {min}\\{\\kappa_B,\\kappa_C \\}$, where event horizon. This implies that the strong cosmic censorship holds in an asymptotically flat spacetime, while it is violated in an asymptotically de Sitter spacetime from the point of view of string theory.

Maeda, K I; Narita, M; Maeda, Kengo; Torii, Takashi; Narita, Makoto

2000-01-01

453

Viscous flow drag reduction by acoustic excitation  

NASA Technical Reports Server (NTRS)

An experimental program in which the effectiveness of a single large eddy break up (LEBU) blade is enhanced by proper acoustic excitation is described. Acoustic waves are generated in response to the incident large scale eddies and directed at the blade trailing edge through the test surface floor below the manipulator blade. The acoustic input is phase locked to the incident flow. Control of the acoustic input apparently allows enhancement of the large eddy cancellation process leading to a decrease of skin friction coefficient. Control of this process with acoustic excitation indicates that vortex unwinding is the mechanism for large eddy destruction in the boundary layer. A deeper understanding of this phenomena could lead to better drag reduction technology and further understanding of the physics of the turbulent boundary layer.

Nagel, Robert T.

1986-01-01

454

Temperature-dependent Coulomb excitations in silicene  

NASA Astrophysics Data System (ADS)

The temperature-dependent Coulomb screening and excitation spectrum of electrons in silicene are studied by the tight-binding model and the random-phase approximation. With the spin-orbit interaction, monolayer silicene is a narrow-gap semiconductor. At finite temperatures, the interplay between the intraband and interband transitions could lead to an undamped plasmon mode at low frequencies. The plasmon mode only exists in a limited region of temperature and momentum, corresponding to the constrained gap transition. Beyond that region, another damped plasmon mode dominates the excitation spectrum. The drastic change in the plasmon behavior might be observed experimentally, which could allow for the identification of the spin-orbit energy gap.

Wu, J. Y.; Chen, S. C.; Lin, M. F.

2014-12-01

455

Earth Rotational Variations Excited by Geophysical Fluids  

NASA Technical Reports Server (NTRS)

Modern space geodetic measurement of Earth rotation variations, particularly by means of the VLBI technique, has over the years allowed studies of Earth rotation dynamics to advance in ever-increasing precision, accuracy, and temporal resolution. A review will be presented on our understanding of the geophysical and climatic causes, or "excitations". for length-of-day change, polar motion, and nutations. These excitations sources come from mass transports that constantly take place in the Earth system comprised of the atmosphere, hydrosphere, cryosphere, lithosphere, mantle, and the cores. In this sense, together with other space geodetic measurements of time-variable gravity and geocenter motion, Earth rotation variations become a remote-sensing tool for the integral of all mass transports, providing valuable information about the latter on a wide range of spatial and temporal scales. Future prospects with respect to geophysical studies with even higher accuracy and resolution will be discussed.

Chao, Benjamin F.

2004-01-01

456

Waking-up to Science!  

NASA Astrophysics Data System (ADS)

The Science on Stage festival as an alarm clock for science teaching How is Europe to tackle its shortage of scientists? The EIROforum Science on Stage festival aims to give European teachers some of the answers they need to take up this urgent challenge. This unique event, showcasing the very best of today's science education, will feature science demonstrations, a science teaching fair with some 66 stands, and a Round Table discussion with the participation of the European Commissioner for Science and Research, Janez Poto?nik. ESO PR Photo 14/07 ESO PR Photo 14/07 Science on Stage will have the city of Grenoble (France) buzzing from 2 to 6 April 2007. A rugby team and a hockey team will take on the power of the vacuum, a cook will demonstrate how science can inspire new culinary ideas, visitors will discover the real colour of the sun, an inflatable model of Borromini's gallery will help to explain the science of optical illusions, and Merlin himself will reveal all about how to make a cake float. These are just some of the exciting things that will be happening at the EIROforum Science on Stage festival. By showing how fascinating and entertaining science can be, the event aims to attract young people to science and ultimately help to reduce the shortage of scientists in Europe. With support from the European Commission, this international festival will bring together some 500 science educators from 27 European countries. The highlight of the festival will be a Round Table discussion on 'Science Education in the Age of the Knowledge Society - Strengthening Science Education in Europe', which will take place on 5 April 2007 with the participation of the European Commissioner for Science and Research, Janez Poto?nik. The panellists - all high-ranking decision-makers - will include the Danish Minister for Education, Bertel Haarder, the MEP Vittorio Prodi, and the Chair of the UK's Engineering and Physical Sciences Research Council, Julia Higgins. "Curiosity is in our genes", says Poto?nik. "Unfortunately it tends to die away when we grow up. This is because the ways we raise and educate our children and the ways we work and live do not always support innovative thinking and doing. We cannot change this overnight. But I think it is worth making the effort to awaken this dormant passion and initiatives like Science on Stage can be a very effective alarm clock", he adds. The festival will close with the presentation of the European Science Teaching Awards. The teaching materials and methods voted to be the best in Europe will then be presented in the 'Science in School' magazine, distributed free of charge to 30,000 teachers in Europe. The festival is the climax of a two-year programme of events organised in virtually every European country and from which delegates have been selected for their outstanding projects for promoting science. The winners of ESO's Catch a Star! 2007 contest will also be announced during the Science on Stage festival. The event follows on from the hugely successful 'Physics on Stage' and 'Science on Stage' festivals organised by EIROforum in 2000, 2002, 2003 and 2005. Journalists are cordially invited to take part in this unique European event. Practical information, including the detailed festival programme, is available on the Science on Stage web site at http://www.ill.fr/scienceonstage2007. A detailed press kit is available at http://www.ill.fr/scienceonstage2007/fichiers/SOSpresskit.pdf

2007-03-01

457

NASA/MSFC/NSSTC Science Communication Roundtable  

NASA Technical Reports Server (NTRS)

For the last several years the Science Directorate at Marshall Space Flight Center has carried out a diverse program of Internet-based science communication. The Directorate's Science Roundtable includes active researchers, NASA public relations, educators, and administrators. The Science@NASA award-winning family of Web sites features science, mathematics, and space news. The program includes extended stories about NASA science, a curriculum resource for teachers tied to national education standards, on-line activities for students, and webcasts of real-time events. Science stories cover a variety of space-related subjects and are expressed in simple terms everyone can understand. The sites address such questions as: what is space weather, what's in the heart of a hurricane, can humans live on Mars, and what is it like to live aboard the International Space Station? Along with a new look, the new format now offers articles organized by subject matter, such as astronomy, living in space, earth science or biology. The focus of sharing real-time science related events has been to involve and excite students and the public about science. Events have involved meteor showers, solar eclipses, natural very low frequency radio emissions, and amateur balloon flights. In some cases broadcasts accommodate active feedback and questions from Internet participants. Information will be provided about each member of the Science@NASA web sites.

Adams, Mitzi L.; Gallagher, D. L.; Koczor, R. J.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

458

Impulse excitation of piezoelectric bimorphs for energy harvesting: a dimensionless model  

NASA Astrophysics Data System (ADS)

Energy harvesting (EH) is a multidisciplinary research area, involving physics, materials science and engineering, with the objective of providing renewable sources of power sufficient to operate targeted low-power applications. Piezoelectric transducers are often used for inertial vibrational as well as direct excitation EH. However, due to the stiffness of the most common material (PZT), compact and light-weight harvesters have high resonant frequencies, making them inefficient at extracting low-frequency power from the environment. The technique of frequency up-conversion, in the form of either plucking or impulse excitation, aims to bridge this frequency gap. In this paper, the technique is modelled analytically with focus on impulse excitation via impact or shock. An analytical model is developed in a standard way starting from the Euler-Bernoulli beam equations adapted to a piezoelectric bimorph. A set of dimensionless variables and parameters is defined and a system of differential equations derived. Here the system is solved numerically for a wide range of the two group parameters present, covering piezoelectric coupling strength between PVDF and PMN-PT. One major result is that the strength of the coupling strongly affects the timescale of the process, but has only a minor effect on the total energy converted. The model can be readily adapted to different excitation profiles.

Pozzi, Michele

2014-04-01

459

Interaction of highly vibrationally excited molecules with clean metal surfaces. Final technical report  

SciTech Connect

The authors present results from a grant funded under the Department of Energy Office of Basic Energy Sciences. A collaboration between Prof. Alec Wodtke of the Department of Chemistry at UCSB and Daniel J. Auerbach of IBM Almaden Research Labs has allowed new experiments on the dynamics of surface chemical reactivity to be successfully executed. High quality data has been generated which provides an excellent test of theoretical models of surface reactivity, a topic of importance to catalysis. The authors have obtained the first experimental measurements on the influence of reactant velocity on the steric effect in a chemical reaction: the dissociative adsorption of hydrogen on copper. They have also designed and built a molecular beam scattering apparatus for the study of highly vibrationally excited molecules and their interactions with clean and oxidized metal surfaces. With this apparatus they have observed the vibrational energy exchange of highly vibrationally excited NO with an oxidized copper surface. Multi-quantum vibrational relaxation was found ({Delta}v = 1-5). Such remarkably strong and efficient vibrational energy transfer represents a qualitatively new phenomenon and is representative of the exciting new behavior that they had hoped might be observable in this project. Evidence of chemical reactivity of vibrationally excited NO on a clean copper surface was also found.

Wodtke, A.M. [Univ. of California, Santa Barbara, CA (United States). Dept. of Chemistry; Auerbach, D.J. [IBM Almaden Research Center, San Jose, CA (United States)

1998-11-01

460

Excitations in superfluids of atoms and polaritons  

E-print Network

. . . . . . . . . . . . . . . 182 6.3.9 Condensate energy and condensation threshold vs radius . . . . . 183 6.3.10 Flexibility of excitation method and variations of the double-ring geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 6.3.11 Video 1: Sample... that the rules of his/her logical picture are mathematical axioms, which are consistent with experience or experiment and universal in the sense that other human beings might share their meaning. For example when analysing the motion of a planet around a star...

Pinsker, Florian

2014-11-11

461

Magnetoplasmon excitations in quantum dot arrays  

Microsoft Academic Search

Motivated by the far-infrared transmission experiments of Demel et al., we have investigated the magnetoplasmon excitations in an array of quantum dots within the ThomasFermiDiracvon Weizscker (TFDW) approximation. Detailed calculations of the magnetic dispersion and power absorption from a uniform radiation field unambiguously demonstrates that the noncircular symmetry of the individual dots is responsible for the anticrossing behaviour observed in

B. P van Zyl; E. Zaremba

2000-01-01

462

When inhibition not excitation synchronizes neural firing  

Microsoft Academic Search

Excitatory and inhibitory synaptic coupling can have counter-intuitive effects on the synchronization of neuronal firing. While it might appear that excitatory coupling would lead to synchronization, we show that frequently inhibition rather than excitation synchronizes firing. We study two identical neurons described by integrate-and-fire models, general phase-coupled models or the Hodgkin-Huxley model with mutual, non-instantaneous excitatory or inhibitory synapses between

CARL VAN VREESWIJK; L. F. Abbott; G. Bard Ermentrout

1994-01-01

463

Collective excitations of the element Z = 120  

Microsoft Academic Search

The low-lying vibrational excitations of superheavy even-even nuclei around Z=120 and N=172, predicted to be spherical by the relativistic mean-field (RMF) model, are studied within a phenomenological collective\\u000a approach. In the framework of the macroscopic model for giant resonances, we compute the transition densities of the isoscalar\\u000a monopole, quadrupole, and octupole and isovector dipole modes for the superheavy nucleus 292120,

?. Mi?icu; T. Brvenich; T. Cornelius; W. Greiner

2003-01-01

464

Correlated phases and excitations in the iridates  

NASA Astrophysics Data System (ADS)

The iridium oxides form an intriguing set of materials controlled by a delicate balance of kinetic, spin-orbit, and Coulomb interaction energies. Many possible exotic phases and phenomena have been suggested for them in the literature. I will review the theoretical context for these compounds, emphasizing effects arising from the combination of strong spin-orbit coupling and electron-electron correlations. Finally, I will discuss our group's on-going efforts to understand the excitations and magnetic phases in these materials.

Balents, Leon

2013-03-01

465

Monitoring of 6-cm excited OH masers  

Microsoft Academic Search

Six sources with 4765-MHz maser emission from the ^2Pi_1\\/2J=1\\/2 excited level of OH have been monitored for a period of more than a year. One of these sources, G294.51-1.62, is a new detection. No masers were detected at either 4750 or 4660MHz. The narrowest lines are not resolved in the 0.190kms^-1 resolution spectra but their velocities have been constant throughout

Derck P. Smits

1997-01-01

466

Low Energy Excitations in Quantum Condensates  

NASA Astrophysics Data System (ADS)

In this thesis, we theoretically study low energy excitations in two types of quantum condensates, Bose-Einstein condensates and Quantum Hall condensates. First, we investigate the effect of an anisotropic trap on the instability of the polar (mF = 0) phase of a spin-1 Bose-Einstein condensate. By rigorously considering the spatial quantization, we show that the growth of the nascent ferromagnetic phase at short times becomes anisotropic with stronger oscillations in the magnetization correlation function along the unconfined direction. Turning to quantum Hall condensates, we analyze edge excitations in the nu = 1 plateau and demonstrate that two experimentally observed features of edge modes, rapid head decay and long-lived charged excitations, cannot be consistently explained using a model where energy is dissipated from a hard edge via either phonon interactions or bulk AC conductivity. We suggest a soft edge model where heat can decay through intra-edge interactions to explain the discrepancy and calculate the scaling properties of this model. We then demonstrate numerically that non-Abelian quasihole excitations of the nu = 5/2 fractional quantum Hall state have some of the key properties necessary to support quantum computation. We find that as the quasihole spacing is increased, the two orthogonal wavefunctions describing a system with four quasiholes become exponentially degenerate with decay length xiE?2.3?0. Additionally we determine which fusion channel is lower in energy when two quasiholes are brought close together. Finally, we consider a hypothetical topological quantum computer composed of either Ising or Fibonacci anyons. For each case, we calculate the time and number of qubits necessary to execute the most computationally expensive step of Shor's quantum factoring algorithm, modular exponentiation. With reasonable restrictions on the physical parameters we find that factoring a 128 bit number requires approximately 103 Fibonacci anyons versus at least 3 x 109 Ising anyons.

Baraban, Mara S.

467

Collective excitations (plasmons) in solids and nanostructures  

NASA Astrophysics Data System (ADS)

In this work, we summarize the studies on the interaction of moving charged particles with bulk and surface plasmons in systems ranging from macro to nanoscopic scale, analyzing the differences and similarities that arise when the size and shape of the system are modified. In particular, we discuss the strong interference effects in the excitation of plasmons that arise in the interaction of particles with systems of nanoscale dimensions.

Gervasoni, J. L.; Segui, S.; Arista, N.

468

Dynamic hyperpolarizabilities of excited states of hydrogen  

Microsoft Academic Search

On the basis of the generalized Sturm expansion of the radial part of the Coulomb Green function, a computational method is\\u000a proposed and numerical results are presented for the dynamic hyperpolarizability ? and the corrections E\\u000a (4) (quadratic in the light intensity) to the quasi-energy of the ground and excited states of hydrogen with principal quantum\\u000a numbers n?5 in a

N. L. Manakov; S. I. Marmo; E. A. Pronin

2004-01-01

469

Incessant excitation of the Earth's free oscillations  

Microsoft Academic Search

We, for the first time, report the evidence of incessant excitation of the Earth's free oscillations, mainly the fundamental spheroidal modes in a frequency range from 0.3 to 5 mHz, based on the three year record of a superconducting gravimeter at Syowa Station, East Antarctica. The frequency-time spectrogram of this record is striped by more than 30 lines at nGal

K. Nawa; N. Suda; Yoshio Fukao; Tadahiro Sato; Yuichi Aoyama; Kazuo Shibuya

1998-01-01

470

Spiral core in singly diffusive excitable media  

SciTech Connect

We formulate the problem of finding the spiral core which smoothly matches onto the asymptotic rotating solution of the FitzHugh-Nagumo model. We prove that the inner problem (with scale {epsilon}, the ratio of the reaction rates) has a solution for all possible outer solutions on scale {epsilon}{sup 2/3}; furthermore, we explicitly determine this solution via a simple numerical procedure. This completes the rigorous demonstration of the existence of rotating spiral solutions in singly diffusive excitable systems.

Kessler, D.A. (Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)); Levine, H.; Reynolds, W.N. (Department of Physics and Institute for Nonlinear Science, University of California, San Diego, La Jolla, California 92093 (United States))

1992-01-20

471

Excitations in Hot Non-Commutative Theories  

E-print Network

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T_0 ~ (g \\theta)^(-1\\2). We briefly comment on N=2 Yang-Mills at finite density.

Landsteiner, K; Tytgat, M H G; Landsteiner, Karl; Lopez, Esperanza; Tytgat, Michel H.G.

2000-01-01

472

Excitations in Hot Non-Commutative Theories  

E-print Network

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T_0 ~ (g \\theta)^(-1\\2). We briefly comment on N=2 Yang-Mills at finite density.

Karl Landsteiner; Esperanza Lopez; Michel H. G. Tytgat

2000-12-19

473

Excitations in hot non-commutative theories  

Microsoft Academic Search

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In Script N = 4 Yang-Mills the low momentum modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T0 approx (gtheta)-1\\/2. We briefly comment on Script N = 2 Yang-Mills

Karl Landsteiner; Esperanza Lopez; Michel H. G. Tytgat

2000-01-01

474

Excitation of a slow wave structure  

SciTech Connect

The Green's function on a slow wave structure is constructed. The Green's function includes all radial modes, and for each radial mode, all space harmonics. We compare the analytic solution of the frequency response on the slow wave structure with that obtained from a particle-in-cell code. Favorable comparison is obtained when the first few lower order modes are resonantly excited. This gives some confidence in the prediction of converting a pulse train into radiation using a slow wave structure.

Zhang Peng; Lau, Y. Y. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Hoff, Brad; French, D. M. [Air Force Research Laboratory, Kirtland AFB, Albuquerque, New Mexico 87117 (United States); Luginsland, J. W. [Air Force Office of Scientific Research, Arlington, Virginia 22203 (United States)

2012-12-15

475

Dynamical analysis of highly excited molecular spectra  

SciTech Connect

The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

Kellman, M.E. [Univ. of Oregon, Eugene (United States)

1993-12-01

476

Multiphonon excitations in boson quantum films  

SciTech Connect

Dynamical excitations in thin liquid films of {sup 4}He adsorbed to a substrate are investigated by using a microscopic theory of excitations that includes multiple-phonon scattering. We study the dispersion relation, excitation mechanisms, transition densities, and particle currents as a function of surface coverage. A primary new result is that we have included three-phonon scattering processes in the calculation of the dynamic structure function and the one-body current densities. With the exception that our ground state is determined by our variational theory, rather than taken from experiment, our work on the dynamic structure function is the generalization of that of Jackson [Phys. Rev. A {bold 4}, 2386 (1971)] to inhomogeneous systems (films). Using sum rules for the dynamic structure function as a guide, we suggest a simple scaling argument for improving the agreement between our dynamic structure function and the experimental one. The addition of three-phonon contributions bring about the following changes. First, the energy of most modes is lowered by a non-negligible amount for finite momentum excitations. Second, the film{close_quote}s surface mode is the exception; it is only slightly affected. Third, for monolayer films there is large scattering at high energies at intermediate values of momenta. This scattering can be traced back to an anomalously large contribution to the two-particle density of states. Fourth, all modes with energy above a critical energy decay, and the associated peaks of the dynamic structure function are broadened. Fifth, the maxonlike character is enhanced in the bulklike modes. {copyright} {ital 1996 The American Physical Society.}

Clements, B.E. [Institute Laue Langevin, 38042 Grenoble Cedex (France)] [Institute Laue Langevin, 38042 Grenoble Cedex (France); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Krotscheck, E. [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria)] [Institut fuer Theoretische Physik, Johannes Kepler Universitaet, A-4040 Linz (Austria); [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States); Tymczak, C.J. [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)] [Department of Physics, Texas A& M University, College Station, Texas 77843 (United States)

1996-05-01

477

Subdiffraction limited, remote excitation of surface enhanced Raman scattering.  

PubMed

We demonstrate that focused laser excitation at the end of silver nanowires of 50-150 nm diameter excites SERS hot-spots at points of nanoparticle adsorption many micrometers along the wire due to the plasmon waveguide effect. The total SERS intensity detected at the hot-spots following wire-end excitation correlates with the known wavelength, polarization, and distance dependences of surface plasmon polariton (SPP) propagation in nanowires. The SERS spectra obtained at the hot-spots following wire-end excitation show very little background compared to when excitation occurs directly at the hot-spot, suggesting that a much smaller SERS excitation volume is achieved by remote, waveguide excitation. The ability to transfer SERS excitation over several micrometers, through a structure with a subdiffraction limit diameter, is discussed with respect to potential high-resolution SERS imaging applications. PMID:19199757

Hutchison, James A; Centeno, Silvia P; Odaka, Hideho; Fukumura, Hiroshi; Hofkens, Johan; Uji-I, Hiroshi

2009-03-01

478

11. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC GENERATOR SHOWING COPPER COMMUTATOR AND CARBON BRUSHES. VIEW TO NORTHEAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

479

10. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC GENERATOR SHOWING CABLING FROM ARMATURE TO COMMUTATOR. VIEW TO NORTHEAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

480

14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. POWERHOUSE INTERIOR, EXCITER No. 2 SHOWING GENERAL ELECTRIC INDUCTION MOTOR IN SERIES BETWEEN PELTON-DOBLE IMPULSE WHEEL AND GENERAL ELECTRIC GENERATOR. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

481

13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. POWERHOUSE INTERIOR, DETAIL OF EXCITER No. 2 GENERAL ELECTRIC INDUCTION MOTOR NAMEPLATE. VIEW TO EAST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA